gen_initramfs_list.sh: fix the tool name in the comment

There is no tool named "gen_initramfs". The correct name is
"gen_init_cpio".
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Greg Thelen <gthelen@google.com>

usr/gen_initramfs_list.sh

@@ -189,7 +189,7 @@ dir_filelist() {
 
 # if only one file is specified and it is .cpio file then use it direct as fs
 # if a directory is specified then add all files in given direcotry to fs
-# if a regular file is specified assume it is in gen_initramfs format
+# if a regular file is specified assume it is in gen_init_cpio format
 input_file() {
 	source="$1"
 	if [ -f "$1" ]; then