staging: pi433: replace shifting with BIT macro

Fixes checkpatch warnings:

  CHECK: Prefer using the BIT macro
Signed-off-by: Valentin Vidic <Valentin.Vidic@CARNet.hr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/pi433/pi433_if.c

@@ -54,7 +54,7 @@
 #include "pi433_if.h"
 #include "rf69.h"
 
-#define N_PI433_MINORS			(1U << MINORBITS) /*32*/	/* ... up to 256 */
+#define N_PI433_MINORS			BIT(MINORBITS) /*32*/	/* ... up to 256 */
 #define MAX_MSG_SIZE			900	/* min: FIFO_SIZE! */
 #define MSG_FIFO_SIZE			65536   /* 65536 = 2^16  */
 #define NUM_DIO				2