staging: fsl-mc: fix build testing on x86

Selecting GENERIC_MSI_IRQ_DOMAIN on x86 causes a compile-time error in
some configurations:

drivers/base/platform-msi.c:37:19: error: field 'arg' has incomplete type

On the other architectures, we are fine, but here we should have an additional
dependency on X86_LOCAL_APIC so we can get the PCI_MSI_IRQ_DOMAIN symbol.

Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>