common: cosmetic: CONFIG_BOOTFILE checkpatch compliance

Remove MK_STR from places that consume CONFIG_BOOTFILE to force all definitions to be string literals.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/configs/ms7720se.h b/include/configs/ms7720se.h
index dd79b2d..afa82cf 100644
--- a/include/configs/ms7720se.h
+++ b/include/configs/ms7720se.h
@@ -41,7 +41,7 @@
 
 #define CONFIG_BAUDRATE		115200
 #define CONFIG_BOOTARGS		"console=ttySC0,115200"
-#define CONFIG_BOOTFILE		/boot/zImage
+#define CONFIG_BOOTFILE		"/boot/zImage"
 #define CONFIG_LOADADDR		0x8E000000
 
 #define CONFIG_VERSION_VARIABLE