video: Drop DEV_FLAGS_SYSTEM flag

DEV_FLAGS_SYSTEM does not have any actual meaning, hence drop it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/mpl/common/kbd.c b/board/mpl/common/kbd.c
index 99de2ca..1da72c5 100644
--- a/board/mpl/common/kbd.c
+++ b/board/mpl/common/kbd.c
@@ -203,7 +203,7 @@
 		return -1;
 	memset (&kbddev, 0, sizeof(kbddev));
 	strcpy(kbddev.name, DEVNAME);
-	kbddev.flags =  DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
+	kbddev.flags =  DEV_FLAGS_INPUT;
 	kbddev.getc = kbd_getc ;
 	kbddev.tstc = kbd_testc ;