drm/i915/debugfs: Pass guc_log struct to i915_guc_log_info

The log struct is the only thing the function needs (apart from
the seq_file), so we can pass just that instead of the whole dev_priv.

v2: Split this change to its own patch (Michal)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200218223327.11058-1-daniele.ceraolospurio@intel.com