drm/i915/guc: Use streaming loads to speed up dumping the guc log

Use a temporary page and mempy_from_wc to reduce the time it takes to
dump the guc log to debugfs.

Signed-off-by: Chris Wilson <chris.p.wilson@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220728022028.2190627-6-John.C.Harrison@Intel.com