Use correct type to check for all-mask exact match IP addresses.

Fixes following sparse warnings due to big endian value checks
against 0xffffffff in is_addr_all_mask():
cxgb4_filter.c:977:25: warning: restricted __be32 degrades to integer
cxgb4_filter.c:983:37: warning: restricted __be32 degrades to integer
cxgb4_filter.c:984:37: warning: restricted __be32 degrades to integer
cxgb4_filter.c:985:37: warning: restricted __be32 degrades to integer
cxgb4_filter.c:986:37: warning: restricted __be32 degrades to integer

Fixes: 3eb8b62d ("cxgb4: add support to create hash-filters via tc-flower offload")
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>