[Mellanox] Update SAI build procedure (#15728)

= Why I did it
To optimize Mellanox platform SAI build

- How I did it
SAI debs are now downloaded as Spectrum-SDK-Drivers-SONiC-Bins release.

- How to verify it
Configure/build for Mellanox platform, check the image and ensure that correct SAI debs are included.

.gitmodules

@@ -72,9 +72,6 @@
 [submodule "src/scapy"]
 	path = src/scapy
 	url = https://github.com/secdev/scapy.git
-[submodule "platform/mellanox/mlnx-sai/SAI-Implementation"]
-	path = platform/mellanox/mlnx-sai/SAI-Implementation
-	url = https://github.com/Mellanox/SAI-Implementation
 [submodule "src/sonic-mgmt-framework"]
 	path = src/sonic-mgmt-framework
 	url = https://github.com/sonic-net/sonic-mgmt-framework

platform/mellanox/.gitignore

@@ -1,6 +1,4 @@
 # Subdirectories
-mlnx-sai/*
-!mlnx-sai/Makefile
 hw-management/*
 !hw-management/Makefile
 !hw-management/*.patch

platform/mellanox/mlnx-sai.mk

@@ -1,8 +1,21 @@
 # Mellanox SAI
 
 MLNX_SAI_VERSION = SAIBuild2305.24.0.1
+MLNX_SAI_ASSETS_GITHUB_URL = https://github.com/Mellanox/Spectrum-SDK-Drivers-SONiC-Bins
+MLNX_SAI_ASSETS_RELEASE_TAG = sai-$(MLNX_SAI_VERSION)-$(BLDENV)-$(CONFIGURED_ARCH)
+MLNX_SAI_ASSETS_URL = $(MLNX_ASSETS_GITHUB_URL)/releases/download/$(MLNX_SAI_ASSETS_RELEASE_TAG)
+MLNX_SAI_DEB_VERSION = $(subst -,.,$(subst _,.,$(MLNX_SAI_VERSION)))
 
-export MLNX_SAI_VERSION
+# Place here URL where SAI sources exist
+MLNX_SAI_SOURCE_BASE_URL = 
+
+ifneq ($(MLNX_SAI_SOURCE_BASE_URL), )
+SAI_FROM_SRC = y
+else
+SAI_FROM_SRC = n
+endif
+
+export MLNX_SAI_VERSION MLNX_SAI_SOURCE_BASE_URL
 
 MLNX_SAI = mlnx-sai_1.mlnx.$(MLNX_SAI_VERSION)_$(CONFIGURED_ARCH).deb
 $(MLNX_SAI)_SRC_PATH = $(PLATFORM_PATH)/mlnx-sai
@@ -11,4 +24,16 @@ $(MLNX_SAI)_RDEPENDS += $(MLNX_SDK_RDEBS) $(MLNX_SDK_DEBS)
 $(eval $(call add_conflict_package,$(MLNX_SAI),$(LIBSAIVS_DEV)))
 MLNX_SAI_DBGSYM = mlnx-sai-dbgsym_1.mlnx.$(MLNX_SAI_VERSION)_$(CONFIGURED_ARCH).deb
 $(eval $(call add_derived_package,$(MLNX_SAI),$(MLNX_SAI_DBGSYM)))
+
+define make_url
+	$(1)_URL = $(MLNX_SAI_ASSETS_URL)/$(1)
+
+endef
+
+$(eval $(foreach deb,$(MLNX_SAI) $(MLNX_SAI_DBGSYM),$(call make_url,$(deb))))
+
+ifeq ($(SAI_FROM_SRC), y)
 SONIC_MAKE_DEBS += $(MLNX_SAI)
+else
+SONIC_ONLINE_DEBS += $(MLNX_SAI)
+endif

platform/mellanox/mlnx-sai/.gitignore

@@ -0,0 +1,6 @@
+# Ignore everything in this directory
+*
+# Except this file
+!.gitignore
+!Makefile
+

platform/mellanox/mlnx-sai/Makefile

@@ -6,11 +6,11 @@ MAIN_TARGET = mlnx-sai_1.mlnx.$(MLNX_SAI_VERSION)_$(CONFIGURED_ARCH).deb
 DERIVED_TARGETS = mlnx-sai-dbgsym_1.mlnx.$(MLNX_SAI_VERSION)_$(CONFIGURED_ARCH).deb
 
 $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
-	pushd SAI-Implementation
+	rm -rf mlnx_sai
+	wget -c $(MLNX_SAI_SOURCE_BASE_URL)/$(MLNX_SAI_VERSION).tar.gz -O - | tar -xz
 	pushd mlnx_sai
 
 	debuild -e 'make_extra_flags="DEFS=-DACS_OS -DCONFIG_SYSLOG"' -us -uc -d -b
 	popd
 
 	mv $(DERIVED_TARGETS) $* $(DEST)/
-	popd

platform/mellanox/mlnx-sai/SAI-Implementation

@@ -1 +0,0 @@
-Subproject commit ec7fa674f143809e602a56b6ef5d279ade8b77d2