drm/i915/guc: Make GuC log sizes runtime configurable

The GuC log buffer sizes had to be configured statically at compile
time. This can be quite troublesome when needing to get larger logs
out of a released driver. So re-organise the code to allow a boot time
module parameter override.

Signed-off-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/20220728022028.2190627-7-John.C.Harrison@Intel.com