[armhf, arm64] Enable DRM_TEGRA_STAGING

DRM_TEGRA_STAGING must currently be enabled in the kernel and libdrm
must be built with --enable-tegra-experimental-api.  Our libdrm package
already does the latter (at least on armhf), so enable the former as
well.

debian/changelog

@@ -4,6 +4,9 @@ linux (4.7~rc4-1~exp2) UNRELEASED; urgency=medium
   * [mipsel] Remove loongson-2e and loongson-2f flavours (Closes: #827790).
   * [mipsel/4kc-malta, mipsel/5kc-malta] Build for R2 ISA.
 
+  [ Martin Michlmayr ]
+  * [armhf, arm64] Enable DRM_TEGRA_STAGING.
+
  -- Ben Hutchings <ben@decadent.org.uk>  Tue, 21 Jun 2016 20:43:50 +0100
 
 linux (4.7~rc4-1~exp1) experimental; urgency=medium

debian/config/arm64/config

@@ -114,6 +114,7 @@ CONFIG_DRM_MSM_DSI_20NM_PHY=y
 ## file: drivers/gpu/drm/tegra/Kconfig
 ##
 CONFIG_DRM_TEGRA=m
+CONFIG_DRM_TEGRA_STAGING=y
 
 ##
 ## file: drivers/gpu/host1x/Kconfig

debian/config/armhf/config

@@ -318,7 +318,7 @@ CONFIG_ROCKCHIP_DW_HDMI=m
 ##
 CONFIG_DRM_TEGRA=m
 # CONFIG_DRM_TEGRA_DEBUG is not set
-# CONFIG_DRM_TEGRA_STAGING is not set
+CONFIG_DRM_TEGRA_STAGING=y
 
 ##
 ## file: drivers/gpu/drm/tilcdc/Kconfig