octeontx2-af: Add validation of lmac

With the addition of new MAC blocks like CN10K RPM and CN10KB
RPM_USX, LMACs are noncontiguous. Though in most of the functions,
lmac validation checks exist but in few functions they are missing.
This patch adds the same.

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>