Changing the i915_edp_psr_debug was enabling, disabling or switching
PSR version by directly calling intel_psr_disable_locked() and
intel_psr_enable_locked(), what is not the default PSR path that will
be executed by real users.

So lets force a fastset in the PSR CRTC to trigger a pipe update and
stress the default code path.

Recently a bug was found when switching from PSR2 to PSR1 while
enable_psr kernel parameter was set to the default parameter, this
changes fix it and also fixes the bug linked bellow were DRRS was
left enabled together with PSR when enabling PSR from debugfs.

v2: Handling missing case: disabled to PSR1

v3: Not duplicating the whole atomic state(Maarten)

v4: Adding back the missing call to intel_psr_irq_control(Dhinakaran)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108341
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190206211845.5322-1-jose.souza@intel.com