gfx: drv: DPST 3.0 kernel side support

gfx: drv: DPST 3.0 kernel side support

This patch removes the dead UMG workqueue implementation and adds support
for sending signals to userspace on DPST interrupts. The DRM fasync
infrastructure is used for this.

SIGIO/POLL_IN is sent on histogram interrupts and SIGIO/POLL_OUT on
phase-in interrupts.

Issue: ANDROID-2333
Signed-off-by: Antti Koskipaa <antti.koskipaa@linux.intel.com>
Signed-off-by: Yong-Joon.Park <yong-joon.park@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(with a claim he does not know DPST)
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>