drm/i915: add yesno utility function

Add a common function to return "yes" or "no" string based on the
argument, and drop the local versions of it.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
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 d2c4449..1d99402 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -106,6 +106,11 @@
 	unlikely(__ret_warn_on);					\
 })
 
+static inline const char *yesno(bool v)
+{
+	return v ? "yes" : "no";
+}
+
 enum pipe {
 	INVALID_PIPE = -1,
 	PIPE_A = 0,