powerpc/configs/6xx: Turn CONFIG_DRM_RADEON back on

In commit d92d9c3a ("drm: hide legacy drivers with CONFIG_DRM_LEGACY")
CONFIG_DRM_RADEON was moved behind CONFIG_DRM_LEGACY meaning it
stopped being enabled by ppc6xx_defconfig. Although no one has
noticed, given this is basically a legacy platform, it seems anyone
who is using it probably still wants this driver. So turn it back on
for now.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/ppc6xx_defconfig

@@ -744,9 +744,10 @@ CONFIG_MFD_SM501_GPIO=y
 CONFIG_AGP=y
 CONFIG_AGP_UNINORTH=y
 CONFIG_DRM=m
+CONFIG_DRM_RADEON=m
+CONFIG_DRM_LEGACY=y
 CONFIG_DRM_TDFX=m
 CONFIG_DRM_R128=m
-CONFIG_DRM_RADEON=m
 CONFIG_DRM_MGA=m
 CONFIG_DRM_SIS=m
 CONFIG_DRM_VIA=m