drm/i915/uc: Sanitize uC together with GEM

Instead of dancing around uC on reset/suspend/resume scenarios,
explicitly sanitize uC when we sanitize GEM to force uC reload
and start from known beginning.

v2: don't forget about reset path (Daniele)
    sanitize uc before gem initiated full reset (Daniele)
v3: drop redundant disable_communication in init_hw (Daniele)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180312130308.22952-3-michal.wajdeczko@intel.com