bnxt: Change fw_cap to u64 to accommodate more capability bits

The current fw_cap field (u32) has run out of bits to save any
new capability.

Change the field to u64.

Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>