global: Convert simple_strtoul() with decimal to dectoul()

It is a pain to have to specify the value 10 in each call. Add a new
dectoul() function and update the code to use it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-kirkwood/cpu.c b/arch/arm/mach-kirkwood/cpu.c
index 339ae7f..3953aa9 100644
--- a/arch/arm/mach-kirkwood/cpu.c
+++ b/arch/arm/mach-kirkwood/cpu.c
@@ -125,7 +125,7 @@
 		return;
 
 	/* read sysrstdelay value */
-	sysrst_dly = (u32) simple_strtoul(s, NULL, 10);
+	sysrst_dly = (u32)dectoul(s, NULL);
 
 	/* read SysRst Length counter register (bits 28:0) */
 	sysrst_cnt = (0x1fffffff & readl(KW_REG_SYSRST_CNT));