drm/radeon: add missing hdmi callbacks for rv6xx

When dpm was merged, I added a new asic struct for
rv6xx, but it never got properly updated when the
hdmi callbacks were added due to the two patch sets
being developed in parallel.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=69729

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_asic.c

@@ -1004,6 +1004,8 @@ static struct radeon_asic rv6xx_asic = {
 		.wait_for_vblank = &avivo_wait_for_vblank,
 		.set_backlight_level = &atombios_set_backlight_level,
 		.get_backlight_level = &atombios_get_backlight_level,
+		.hdmi_enable = &r600_hdmi_enable,
+		.hdmi_setmode = &r600_hdmi_setmode,
 	},
 	.copy = {
 		.blit = &r600_copy_cpdma,