mask interrupts on S3 resume

i8259 clears interrupt mask on reset. Interrupt need to be
masked again before enabling interrupts on CPU. Since option
roms are called with interrupts enabled, resume should mask
interrupts in i8259 before calling vgabios.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>