ITE IT8661F changes to match the common code structure.

ITE IT8661F changes to match the common code structure.

 - it8661f_enable_serial() is now in the usual format, using pnp_* functions.

 - Factor out pnp_enter_ext_func_mode()/pnp_exit_ext_func_mode().

 - Factor out it8661f_set_clkin() to set the CLKIN to 24/48MHz.

 - Factor out it8661f_enable_logical_devices(), might not be needed though.
   We leave it here until it's confirmed on hardware that it's not needed.

 - Move some #defines to it8661f.h.

 - Drop no longer used it8661f_sio_write().

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6053 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1