staging: panel: fix interruptible_sleep_on race

interruptible_sleep_on is racy and going away. This replaces the one
caller in the panel driver with the appropriate wait_event_interruptible
variant.

Signed-off-by: Arnd Bergmann <[e-mail]>
Cc: [e-mail]
Cc: Willy Tarreau <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/panel/panel.c

···
 		if (file->f_flags & O_NONBLOCK)
 			return -EAGAIN;
 
-		interruptible_sleep_on(&keypad_read_wait);
-		if (signal_pending(current))
+		if (wait_event_interruptible(keypad_read_wait,
+					     keypad_buflen != 0))
 			return -EINTR;
 	}