x86: Fix S3 resume for HPET MSI IRQ case

x86: Fix S3 resume for HPET MSI IRQ case

Jan Beulich found that for S3 resume on platforms without ARAT feature
but with MSI capable HPET, request_irq() will be called in
hpet_setup_msi_irq() for irq already setup(no release_irq() called
during S3 suspend), so that always falling back to using
legacy_hpet_event.

Fix it by conditional calling request_irq() for 4.1. Planned to split
the S3 resume path from booting path post 4.1, as Jan suggested.

Signed-off-by: Wei Gang <gang.wei@intel.com>
Acked-by: Jan Beulich <jbeulich@novell.com>