sunxi: Move sys_config intialization to arch level

Move sys_config fex stuff initialization to arch level to
enable it for subsys level drivers

Signed-off-by: Alexandr V. Shutko <alex@shutko.ru>
gpio:sunxi: Move driver initialization to subsys level

Move driver initialization to subsys level to be available
for device drivers at fs,device,late levels

Signed-off-by: Alexandr V. Shutko <alex@shutko.ru>