staging: mt7621-pci: IF statement expression comparing to NULL

Remove comparison to NULL in the if statement expression
to match the Linux Kernel coding style.
CHECK: Comparison to NULL could be written "res"
Signed-off-by: Branden Bonaby <brandonbonaby94@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci/pci-mt7621.c

@@ -275,7 +275,7 @@ static int mt7621_pci_parse_request_of_pci_ranges(struct mt7621_pcie *pcie)
 			break;
 		}
 
-		if (res != NULL)
+		if (res)
 			of_pci_range_to_resource(&range, node, res);
 	}