can: flexcan: FLEXCAN_IFLAG_MB: add () around macro argument

This patch fixes the following checkpatch warning:

| Macro argument 'x' may be better as '(x)' to avoid precedence issues

Fixes: cbffaf7a ("can: flexcan: Always use last mailbox for TX")
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/flexcan.c

@@ -140,7 +140,7 @@
 #define FLEXCAN_TX_MB				63
 #define FLEXCAN_RX_MB_OFF_TIMESTAMP_FIRST	(FLEXCAN_TX_MB_RESERVED_OFF_TIMESTAMP + 1)
 #define FLEXCAN_RX_MB_OFF_TIMESTAMP_LAST	(FLEXCAN_TX_MB - 1)
-#define FLEXCAN_IFLAG_MB(x)		BIT(x & 0x1f)
+#define FLEXCAN_IFLAG_MB(x)		BIT((x) & 0x1f)
 #define FLEXCAN_IFLAG_RX_FIFO_OVERFLOW	BIT(7)
 #define FLEXCAN_IFLAG_RX_FIFO_WARN	BIT(6)
 #define FLEXCAN_IFLAG_RX_FIFO_AVAILABLE	BIT(5)