octeontx2-af: Create BPIDs free pool

In current driver 64 BPIDs are reserved for LBK interfaces.
These bpids are 1-to-1 mapped to LBK interface channel numbers.
In some usecases one LBK interface required more than one
bpids and in some case they may not require at all.
These usescase can't be address with the current implementation
as it always reserves only one bpid per LBK channel.
This patch addresses this issue by creating free bpid pool from these
64 bpids instead of 1-to-1 mapping to the lbk channel.
Now based on usecase LBK interface can request a bpid using (bp_enable()).

This patch also reduces the number of bpids for cgx interfaces to 8
and adds proper error code

Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>