drm/i915/dsi: Move intel_dsi_clear_device_ready()

Move the intel_dsi_clear_device_ready() function to higher up in
intel_dsi.c this pairs it with intel_dsi_device_ready(); and pairs
intel_dsi_*enable* with intel_dsi_*disable without
intel_dsi_clear_device_ready() sitting in the middle of them.

This commit purely moves code around, it does not make any
changes what-so-ever.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Bob Paauwe <bob.j.paauwe@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/f971d18ea6d350890447860aeb541dba072a6e47.1488273823.git.jani.nikula@intel.com