arm: delay: annotate delay constant as unsigned long

Currently the __udelay function causes the following compiler warning
when HZ is set to 1000:

arch/arm/lib/delay.c: In function __udelay:
arch/arm/lib/delay.c:88: warning: integer overflow in expression

The overflow does not occur if the constant is unsigned.

Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
index 59fdf64..fc9a37c 100644
--- a/arch/arm/lib/delay.c
+++ b/arch/arm/lib/delay.c
@@ -85,6 +85,6 @@
  */
 void __udelay(unsigned long usecs)
 {
-	__const_udelay(usecs * ((2199023*HZ)>>11));
+	__const_udelay(usecs * ((2199023UL*HZ)>>11));
 }
 EXPORT_SYMBOL(__udelay);