drm: store encoder name in encoder struct

This makes drm_get_encoder_name() thread safe.

Reference: http://lkml.kernel.org/r/645ee6e22cad47d38a2b35c21c8d5fe3@DC1-MBX-01\
.ptsecurity.ru
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/drm/drm_crtc.h

@@ -400,6 +400,7 @@ struct drm_encoder_funcs {
  * @dev: parent DRM device
  * @head: list management
  * @base: base KMS object
+ * @name: encoder name
  * @encoder_type: one of the %DRM_MODE_ENCODER_<foo> types in drm_mode.h
  * @possible_crtcs: bitmask of potential CRTC bindings
  * @possible_clones: bitmask of potential sibling encoders for cloning
@@ -416,6 +417,7 @@ struct drm_encoder {
 	struct list_head head;
 
 	struct drm_mode_object base;
+	char *name;
 	int encoder_type;
 	uint32_t possible_crtcs;
 	uint32_t possible_clones;