net/mlx5: E-Switch, Move source port on reg_c0 to the upper 16 bits

Multi chain support requires the miss path to continue the processing
from the last chain id, and for that we need to save the chain
miss tag (a mapping for 32bit chain id) on reg_c0 which will
come in a next patch.

Currently reg_c0 is exclusively used to store the source port
metadata, giving it 32bit, it is created from 16bits of vcha_id,
and 16bits of vport number.

We will move this source port metadata to upper 16bits, and leave the
lower bits for the chain miss tag. We compress the reg_c0 source port
metadata to 16bits by taking 8 bits from vhca_id, and 8bits from
the vport number.

Since we compress the vport number to 8bits statically, and leave two
top ids for special PF/ECPF numbers, we will only support a max of 254
vports with this strategy.

Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Oz Shlomo <ozsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>