iwlwifi: pcie: don't service an interrupt that was masked

commit 3b57a10ca14c619707398dc58fe5ece18c95b20b upstream.

Sometimes the register status can include interrupts that
were masked. We can, for example, get the RF-Kill bit set
in the interrupt status register although this interrupt
was masked. Then if we get the ALIVE interrupt (for example)
that was not masked, we need to *not* service the RF-Kill
interrupt.
Fix this in the MSI-X interrupt handler.

Cc: stable@vger.kernel.org
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>