rtl8192cu: Fix unbalanced irq enable in error path of rtl92cu_hw_init()

commit 3234f5b06fc3094176a86772cc64baf3decc98fc upstream.

Fixes: a53268be0cb9 ('rtlwifi: rtl8192cu: Fix too long disable of IRQs')
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>