drm/i915/spt+: Don't reset invalid AUX channel interrupt bits in SDEIMR

drm/i915/spt+: Don't reset invalid AUX channel interrupt bits in SDEIMR

The SDE interrupt bits 25, 26 and 27 are either reserved or meant for
DDI E hotplug in SPT+. These bits are meant for AUX channels only in LPT
and CPT, so add the appropriate checks.

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170909004255.14827-1-dhinakaran.pandiyan@intel.com