mlx5: minor fixes (mainly avoidance of hidden casts)

There were many places where parameters which should be u8/u16 were
integer type.

Additionally, in 2 places, a check for a non-null pointer was added
before dereferencing the pointer (this is actually a bug fix).

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Eli Cohen <eli@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
index f2cfd36..166335a 100644
--- a/drivers/infiniband/hw/mlx5/main.c
+++ b/drivers/infiniband/hw/mlx5/main.c
@@ -478,7 +478,7 @@
 	int uuarn;
 	int err;
 	int i;
-	int reqlen;
+	size_t reqlen;
 
 	if (!dev->ib_active)
 		return ERR_PTR(-EAGAIN);