mei: me: make mei_me_fw_sku_sps_4() less cryptic

Last add mei_me_fw_sku_sps_4() kdoc and add descriptive defines
for register name and values.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20200619165121.2145330-3-tomas.winkler@intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>