drm/i915/icl: GSE interrupt moves from DE_MISC to GU_MISC

The Graphics System Event(GSE) interrupt bit has a new location in the
GU_MISC_INTERRUPT_{IIR, ISR, IMR, IER} registers. Since GSE was the only
DE_MISC interrupt that was enabled, with this change we don't enable/handle
any of DE_MISC interrupts for gen11. Credits to Paulo for pointing out
the register change.

v2: from DK
raw_reg_[read/write], branch prediction hint and drop platform check (Mika)

v3: From DK
Early re-enable of master interrupt (Chris)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
[Paulo: bikesheds and rebases]
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180616000530.5357-1-paulo.r.zanoni@intel.com