x86: hpet: Mark per cpu interrupts IRQF_TIMER to prevent resume failure

timer interrupts are excluded from being disabled during suspend. The
clock events code manages the disabling of clock events on its own
because the timer interrupt needs to be functional before the resume
code reenables the device interrupts.

The hpet per cpu timers request their interrupt without setting the
IRQF_TIMER flag so suspend_device_irqs() disables them as well which
results in a fatal resume failure on the boot CPU.

Adding IRQF_TIMER to the interupt flags when requesting the hpet per
cpu timer interrupts solves the problem.

Reported-by: Benjamin S. <sbenni@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Benjamin S. <sbenni@gmx.de>
Cc: stable@kernel.org