rtlwifi: rtl8192ce: Fix missing interrupt ready flag

Proper operation with the rewritten PCI mini driver requires that a flag be set
when interrupts are enabled. This flag was missed.  This patch is one of three needed to
fix the kernel regression reported at https://bugzilla.kernel.org/show_bug.cgi?id=88951.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: Catalin Iacob <iacobcatalin@gmail.com>
Tested-by: Catalin Iacob <iacobcatalin@gmail.com>
Cc: Catalin Iacob <iacobcatalin@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>