net: thunderx: Add support for 16 LMACs of 83xx

83xx will have 4 BGX blocks i.e 16 LMACs, to avoid changing
the same with every platform, nicpf struct elements which
track LMAC related info are now allocated runtime based
on platform's max possible BGX count.

Also fixed configuring min packet size for all LMAC's
supported on a platform.

Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>