rtlwifi: rtl8192cu: Fix too long disable of IRQs

In commit f78bccd7 entitled "rtlwifi:
rtl8192ce: Fix too long disable of IRQs", Olivier Langlois
<olivier@trillion01.com> fixed a problem caused by an extra long disabling
of interrupts. This patch makes the same fix for rtl8192cu.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>