Disabled polled_irq_mode for all Arista DNX devices as this mode leads to excessive use of the CPU via an unneeded interrupt polling thread.
Port indexes of front panel ports are not contiguous in multi-asic because we didn't distiguish between front panel and internal ports, e.g., recycle ports. Fix this by assigning index to front panel port first and then internal ports.
Add 36 port 400g SKU for x86_64-arista_7800r3a_36d series of Linecards.