bnxt_en: Add context memory initialization infrastructure.

Currently, the driver calls memset() to set all relevant context memory
used by the chip to the initial value.  This can take many milliseconds
with the potentially large number of context pages allocated for the
chip.

To make this faster, we only need to initialize the "context kind" field
of each block of context memory.  This patch sets up the infrastructure
to do that with the bnxt_mem_init structure.  In the next patch, we'll
add the logic to obtain the offset of the "context kind" from the
firmware.  This patch is not changing the current behavior of calling
memset() to initialize all relevant context memory.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>