latona: decrease overclock to 1.1GHz

The device wasn't perfectly stable at 1.2GHz.
At 1.1GHz there are no issues with SmartReflex, so re-enable it.
gpu: pvr: allow to change SGX functional clock rate

Allow also to use corex2_fck as parent clock sgx_fck.
Using corex2_fck will allow to increase sgx_fck up to 266MHz.
gpu: pvr: allow to use corex2_fck as parent clock for sgx_fck
gpu: pvr: OMAP3: make ACTIVE_POWER_LATENCY a module param
gpu: pvr: define module params only when required
drivers: add SIO switch driver
drivers: fsa9480: fix typo
board-latona-peripherals: add SIO switch support
latona defconfigs: enable SIO switch driver
Revert "latona: mux: set OMAP_GPIO_UART_SEL to low"

It can now be done from userland.

This reverts commit a19403040da541e479df5fa17f2f4b7b207f9e5e.
latona: code cleanup