drm/i915/context: fix kernel-doc parameter descriptions

drivers/gpu/drm/i915/gt/intel_context.h:108: warning: Function parameter or member 'ce' not described in 'intel_context_lock_pinned'
drivers/gpu/drm/i915/gt/intel_context.h:123: warning: Function parameter or member 'ce' not described in 'intel_context_is_pinned'
drivers/gpu/drm/i915/gt/intel_context.h:142: warning: Function parameter or member 'ce' not described in 'intel_context_unlock_pinned'

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8359a1cef6b5ab268a9dcc1a382281b6e39cfa64.1683041799.git.jani.nikula@intel.com