pwm: imx: Fix the macro MX3_PWMCR_PRESCALER(x) definition

This patch adds missing parentheses around the argument of the macro
MX3_PWMCR_PRESCALER(x) to avoid any potential macro expansion issue.
Reported-by: Lothar Waßmann <LW@KARO-electronics.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Shawn Guo <shawn.guo@freescale.com>
Cc: Lothar Waßmann <LW@KARO-electronics.de>
Cc: linux-pwm@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Acked-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-imx.c

@@ -32,7 +32,7 @@
 #define MX3_PWMCR                 0x00    /* PWM Control Register */
 #define MX3_PWMSAR                0x0C    /* PWM Sample Register */
 #define MX3_PWMPR                 0x10    /* PWM Period Register */
-#define MX3_PWMCR_PRESCALER(x)    (((x - 1) & 0xFFF) << 4)
+#define MX3_PWMCR_PRESCALER(x)    ((((x) - 1) & 0xFFF) << 4)
 #define MX3_PWMCR_DOZEEN                (1 << 24)
 #define MX3_PWMCR_WAITEN                (1 << 23)
 #define MX3_PWMCR_DBGEN			(1 << 22)