drm/i915/uc: Use platform specific defaults for GuC/HuC enabling

The meaning of 'default' for the enable_guc module parameter has been
updated to accurately reflect what is supported on current platforms.
So start using the defaults instead of forcing everything off.
Although, note that right now, the default is for everything to be off
anyway. So this is not a change for current platforms.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210603164812.19045-2-matthew.brost@intel.com