drm/i915: add always-on power wells instead of special casing them

Instead of using a separate function to check whether a power domain is
is always on, add an always-on power well covering all these power
domains and do the usual get/put on these unconditionally. Since we
don't assign a .set handler for these the get/put won't have any effect
besides the adjusted refcount.

This makes the code more readable and provides debug info also on the
use of always-on power wells (once the relevant debugfs entry is added.)

v3: make is_always_on to be bool instead of a bit field (Paulo)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Paulo Zanoni <paulo.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index bb09dbf..e3e732b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -951,6 +951,7 @@
 /* Power well structure for haswell */
 struct i915_power_well {
 	const char *name;
+	bool always_on;
 	/* power well enable/disable usage count */
 	int count;
 	unsigned long domains;