tty: serial: samsung: Fix driver data macros style

Make checkpatch happy by fixing this error:

    ERROR: Macros with complex values should be enclosed in parentheses

Although this change is made to keep macros consistent with consequent
patches (adding driver data for new SoC), it's intentionally added as a
separate patch to ease possible porting efforts in future.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20210811114827.27322-6-semen.protsenko@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/samsung_tty.c

@@ -2820,8 +2820,8 @@ static struct s3c24xx_serial_drv_data exynos5433_serial_drv_data = {
 #define EXYNOS4210_SERIAL_DRV_DATA ((kernel_ulong_t)&exynos4210_serial_drv_data)
 #define EXYNOS5433_SERIAL_DRV_DATA ((kernel_ulong_t)&exynos5433_serial_drv_data)
 #else
-#define EXYNOS4210_SERIAL_DRV_DATA (kernel_ulong_t)NULL
-#define EXYNOS5433_SERIAL_DRV_DATA (kernel_ulong_t)NULL
+#define EXYNOS4210_SERIAL_DRV_DATA ((kernel_ulong_t)NULL)
+#define EXYNOS5433_SERIAL_DRV_DATA ((kernel_ulong_t)NULL)
 #endif
 
 #ifdef CONFIG_ARCH_APPLE