mlxsw: spectrum_acl: Add region association callback

In Spectrum-2, ACL regions that use 8 or 12 key blocks require several
consecutive hardware regions.

In order to allow defragmentation, the device stores a mapping from a
logical region ID to an hardware region ID, which is similar to the page
table that is used to translate virtual addresses to physical addresses.

Add the region association callback to the region create sequence and
implement it as a NOP in Spectrum which does not require it.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>