drm/i915/fbc: rename the FBC disable functions

Instead of:
 - intel_fbc_disable_crtc(crtc)
 - intel_fbc_disable(dev_priv)
we now have:
 - intel_fbc_disable(crtc)
 - intel_fbc_global_disable(dev_priv)

This is because all the other functions that take a CRTC are called
 - intel_fbc_something(crtc)
Instead of:
 - intel_fbc_something_crtc(crtc)

And I also hope that the word "global" is going to help make it more
explicit that "global" is the unusual case, not the opposite.

Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453210558-7875-14-git-send-email-paulo.r.zanoni@intel.com

drivers/gpu/drm/i915/i915_suspend.c

@@ -92,7 +92,7 @@ static void i915_restore_display(struct drm_device *dev)
 	}
 
 	/* only restore FBC info on the platform that supports FBC*/
-	intel_fbc_disable(dev_priv);
+	intel_fbc_global_disable(dev_priv);
 
 	/* restore FBC interval */
 	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))