octeontx2-af: fix lbk link credits on cn10k

[ Upstream commit 87e12a17 ]

Fix LBK link credits on CN10K to be same as CN9K i.e
16 * MAX_LBK_DATA_RATE instead of current scheme of
calculation based on LBK buf length / FIFO size.

Fixes: 6e54e1c5

 ("octeontx2-af: cn10K: Add MTU configuration")
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>