Tweak MHDP driver Kconfig so it can be enabled with etnaviv

The MHDP driver is needed for using HDMI on the i.MX8MQ EVK, tweak its
Kconfig entry so that it can be enabled when using etnaviv, not just
Vivante.

Upstream-Status: pending
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
---

diff --git a/drivers/gpu/drm/imx/mhdp/Kconfig b/drivers/gpu/drm/imx/mhdp/Kconfig
index 225ccc3638a8..164b42f04e94 100644
--- a/drivers/gpu/drm/imx/mhdp/Kconfig
+++ b/drivers/gpu/drm/imx/mhdp/Kconfig
@@ -7,6 +7,6 @@ config DRM_IMX_CDNS_MHDP
 	select DRM_CDNS_HDMI
 	select DRM_CDNS_AUDIO
 	select DRM_CDNS_HDMI_HDCP
-	depends on DRM_IMX
+	depends on DRM_IMX || DRM_ETNAVIV
 	help
 	  Choose this if you want to use HDMI on i.MX8.