Ignore bootloader passed args

Added kernel config option to ignore kernel
command line args passed by the bootloader.

arch/arm/Kconfig

@@ -1083,6 +1083,13 @@ config CMDLINE
 	  time by entering them here. As a minimum, you should specify the
 	  memory size and the root device (e.g., mem=64M root=/dev/nfs).
 
+config IGNORE_BOOT_ARGS
+    bool "Ignore bootloader command line args"
+    default n
+    help
+      Ignore the command line args passed from the bootloader and use
+      default command line args defined in CONFIG_CMDLINE
+
 config XIP_KERNEL
 	bool "Kernel Execute-In-Place from ROM"
 	depends on !ZBOOT_ROM

arch/arm/kernel/setup.c

@@ -613,7 +613,9 @@ __tagtable(ATAG_REVISION, parse_tag_revision);
 
 static int __init parse_tag_cmdline(const struct tag *tag)
 {
+#ifndef CONFIG_IGNORE_BOOT_ARGS
 	strlcpy(default_command_line, tag->u.cmdline.cmdline, COMMAND_LINE_SIZE);
+#endif
 	return 0;
 }