drm/i915/glk: Fix DSI "*ERROR* ULPS is still active" messages

drm/i915/glk: Fix DSI "*ERROR* ULPS is still active" messages

The sequence in glk_dsi_device_ready() enters ULPS then waits until it is
*not* active to then disable it. The correct sequence according to the
spec is to enter ULPS then wait until the GLK_ULPS_NOT_ACTIVE bit is
zero, i.e., ULPS is active, and then disable ULPS.

Fixing the condition gets rid of the following spurious error messages:

[drm:glk_dsi_device_ready [i915]] *ERROR* ULPS is still active

Fixes: df7c2f2db18b ("drm/i915/glk: Add MIPIIO Enable/disable sequence")
Cc: Deepak M <m.deepak@intel.com>
Cc: Madhav Chauhan <madhav.chauhan@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: <drm-intel-fixes@lists.freedesktop.org>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Madhav Chauhan <madhav.chauhan@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170428080222.6147-1-ander.conselvan.de.oliveira@intel.com
(cherry picked from commit 3acbec03b3c51559d01c879e9564d9c9610fe8ce)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>