drm/radeon/kms: Fix R600/RV770 startup path & reset

We were calling reset unconditionaly in the startup path
this is bad we need to call GPU reset for a good reason
as after reset the GPU is in unknown states. To avoid any
more bad things to happen we now also unconditionaly
reinitialize the GPU after reset. This patch fix few issues
reported by different people regarding KMS & R6XX/RV7XX hw.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>