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/Kconfig b/drivers/gpu/drm/imx/Kconfig
index 63d5f1b532ee..a18ba56aa218 100644
--- a/drivers/gpu/drm/imx/Kconfig
+++ b/drivers/gpu/drm/imx/Kconfig
@@ -85,7 +85,7 @@ config DRM_IMX_CDNS_MHDP
 	select DRM_CDNS_DP
 	select DRM_CDNS_HDMI
 	select DRM_CDNS_AUDIO
-	depends on DRM_IMX
+	depends on DRM_IMX || DRM_ETNAVIV
 	help
 	  Choose this if you want to use HDMI on i.MX8.