[ARM] omap: fix lots of 'Using plain integer as NULL pointer'

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 7faa53c..69651cf 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -108,7 +108,7 @@
 		struct plat_serial8250_port *p = serial_platform_data + i;
 
 		if (!(info->enabled_uarts & (1 << i))) {
-			p->membase = 0;
+			p->membase = NULL;
 			p->mapbase = 0;
 			continue;
 		}