x86: assign IRQs to HPET timers

The userspace API for the HPET (see Documentation/hpet.txt) did not work. The
HPET_IE_ON ioctl was failing as there was no IRQ assigned to the timer
device. This patch fixes it by allocating IRQs to timer blocks in the HPET.

arch/x86/kernel/hpet.c |   13 +++++--------
drivers/char/hpet.c    |   45 ++++++++++++++++++++++++++++++++++++++-------
include/linux/hpet.h   |    2 +-
3 files changed, 44 insertions(+), 16 deletions(-)

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>