octeontx2-af: CN10KB: Fix FIFO length calculation for RPM2

octeontx2-af: CN10KB: Fix FIFO length calculation for RPM2

RPM0 and RPM1 on the CN10KB SoC have 8 LMACs each, whereas RPM2
has only 4 LMACs. Similarly, the RPM0 and RPM1 have 256KB FIFO,
whereas RPM2 has 128KB FIFO. This patch fixes an issue with
improper TX credit programming for the RPM2 link.

Fixes: b9d0fedc6234 ("octeontx2-af: cn10kb: Add RPM_USX MAC support")
Signed-off-by: Nithin Dabilpuram <ndabilpuram@marvell.com>
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240108073036.8766-1-naveenm@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>