This patch adds NPC MCAM entry management and support for
allocating and freeing them via mailbox. Both contiguous and
non-contiguous allocations are supported. Incase of contiguous,
if request cannot be met then max contiguous number of available
entries are allocated.

High or low priority index allocation w.r.t a reference MCAM index
is also supported.
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>