drm/i915/guc: Unify naming of private GuC action functions

We should avoid using guc_log prefix for functions that don't
operate on GuC log, but rather request action from the GuC.
Better to use guc_action prefix.

v2: rebase + naming compromise
v3: rebase

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180320181419.35576-1-michal.wajdeczko@intel.com