ARM: UniPhier: refactor pinmon command

The return value of get_boot_mode_sel() is used as the index of
the boot_device_table[] array.  Its type should be "int" rather
than "u32".

Use only the iterator "i" for the loop in do_pinmon().

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/arch/arm/include/asm/arch-uniphier/boot-device.h b/arch/arm/include/asm/arch-uniphier/boot-device.h
index 6987f57..7a10f1c 100644
--- a/arch/arm/include/asm/arch-uniphier/boot-device.h
+++ b/arch/arm/include/asm/arch-uniphier/boot-device.h
@@ -8,7 +8,7 @@
 #ifndef _ASM_BOOT_DEVICE_H_
 #define _ASM_BOOT_DEVICE_H_
 
-u32 get_boot_mode_sel(void);
+int get_boot_mode_sel(void);
 
 struct boot_device_info {
 	u32 type;