vt: keyboard, use DECLARE_BITMAP for key_down

key_down is sued as a bitmap using test_bit, set_bit and similar.
So declare it using DECLARE_BITMAP to make it obvious even from the
declaration.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-8-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/vt/keyboard.c

@@ -135,7 +135,7 @@ static struct input_handler kbd_handler;
 static DEFINE_SPINLOCK(kbd_event_lock);
 static DEFINE_SPINLOCK(led_lock);
 static DEFINE_SPINLOCK(func_buf_lock); /* guard 'func_buf'  and friends */
-static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)];	/* keyboard key bitmap */
+static DECLARE_BITMAP(key_down, KEY_CNT);	/* keyboard key bitmap */
 static unsigned char shift_down[NR_SHIFT];		/* shift state counters.. */
 static bool dead_key_next;