drm/i915/guc: Don't store runtime GuC log level in modparam

drm/i915/guc: Don't store runtime GuC log level in modparam

Currently we are using modparam as placeholder for GuC log level.
Stop doing this and keep runtime GuC level in intel_guc_log struct.

v2:
- rename functions intel_guc_log_level_[get|set] to
intel_guc_log_[get|set]_level (Michał Wajdeczko)
- remove GEM_BUG_ON from intel_guc_log_get_level() (Michał Wajdeczko)

Signed-off-by: Piotr Piórkowski <[email protected]>
Cc: Michal Wajdeczko <[email protected]>
Cc: Michał Winiarski <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Chris Wilson <[email protected]>
Reviewed-by: Michal Wajdeczko <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]