Revert "PCI/MSI: Protect msi_desc::masked for multi-MSI"

This reverts commit 3c953477 which is
commit 77e89afc25f30abd56e76a809ee2884d7c1b63ce upstream.

It breaks the Android KABI and is not needed for any current Android
hardware devices, so can be safely reverted.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: If4d9769c8cbfca6872c9a745fec8ab28bc39199e