net: wireless: rt2x00: Staticize rt2x00queue_pause_queue_nocheck()

rt2x00queue_pause_queue_nocheck()is used only in this file.
Fix the following sparse warning:

drivers/net/wireless/rt2x00/rt2x00queue.c:939:6: warning: symbol 'rt2x00queue_pause_queue_nocheck' was not declared. Should it be
static?

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>