[ALSA] snd-hda-intel: use WALLCLK register to check for early irqs

Use 24Mhz WALLCLK register to ignore too early interrupts and
wrong interrupt status. The bad timing confuses the higher ALSA
layer and causes audio skipping. More information about behaviour
and debugging can be found in kernel bz#15912.

https://bugzilla.kernel.org/show_bug.cgi?id=15912

Signed-off-by: Jaroslav Kysela <perex@perex.cz>