drm/i915: Rename i915_gem_context_reference/unreference()

As these are wrappers around kref_get/kref_put() it is preferable to
follow the naming convention and use the same verb get/put in our
wrapper names for manipulating a reference to the context.

s/i915_gem_context_reference/i915_gem_context_get/
s/i915_gem_context_unreference/i915_gem_context_put/

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1469005202-9659-3-git-send-email-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/1469017917-15134-2-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e163a94..2131e7f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3338,12 +3338,14 @@
 	return ctx;
 }
 
-static inline void i915_gem_context_reference(struct i915_gem_context *ctx)
+static inline struct i915_gem_context *
+i915_gem_context_get(struct i915_gem_context *ctx)
 {
 	kref_get(&ctx->ref);
+	return ctx;
 }
 
-static inline void i915_gem_context_unreference(struct i915_gem_context *ctx)
+static inline void i915_gem_context_put(struct i915_gem_context *ctx)
 {
 	lockdep_assert_held(&ctx->i915->drm.struct_mutex);
 	kref_put(&ctx->ref, i915_gem_context_free);