RDMA/umem: Fix signature of stub ib_umem_find_best_pgsz()

The original function returns unsigned long and 0 on failure.

Fixes: 4a35339958 ("RDMA/umem: Add API to find best driver supported page size in an MR")
Link: https://lore.kernel.org/r/0-v1-982a13cc5c6d+501ae-fix_best_pgsz_stub_jgg@nvidia.com
Reviewed-by: Gal Pressman <galpress@amazon.com>
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

include/rdma/ib_umem.h

@@ -68,10 +68,11 @@ static inline int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offs
 		      		    size_t length) {
 	return -EINVAL;
 }
-static inline int ib_umem_find_best_pgsz(struct ib_umem *umem,
-					 unsigned long pgsz_bitmap,
-					 unsigned long virt) {
-	return -EINVAL;
+static inline unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
+						   unsigned long pgsz_bitmap,
+						   unsigned long virt)
+{
+	return 0;
 }
 
 #endif /* CONFIG_INFINIBAND_USER_MEM */