RDMA/bnxt_re: Fix the GID table length

RDMA/bnxt_re: Fix the GID table length

GID table length is reported by FW. The gid index which is passed to the
driver during modify_qp/create_ah is restricted by the sgid_index field of
struct ib_global_route.  sgid_index is u8 and the max sgid possible is
256.

Each GID entry in HW will have 2 GID entries in the kernel gid table.  So
we can support twice the gid table size reported by FW. Also, restrict the
max GID to 256 also.

Fixes: 847b97887ed4 ("RDMA/bnxt_re: Restrict the max_gids to 256")
Link: https://patch.msgid.link/r/1728373302-19530-11-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>