drm/i915/guc: Improve GuC loading status check/error reports

drm/i915/guc: Improve GuC loading status check/error reports

If the GuC fails to load, it is useful to know what firmware file /
version was attempted. So move the version info report to before the
load attempt rather than only after a successful load.

If the GuC does fail to load, then make the error messages visible
rather than being 'debug' prints that do not appears in dmesg output
by default.

When waiting for the GuC to load, it used to be necessary to check for
two different states - READY and (LAPIC_DONE | MIA_CORE). Apparently
the second signified init complete on RC6 exit. However, in more
recent GuC versions the RC6 exit sequence now finishes with status
READY as well. So the test can be simplified.

Also, add an enum giving all the current status codes that GuC loading
can report as a reference without having to pull and search through
the GuC source files.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220107000622.292081-4-John.C.Harrison@Intel.com