arch/x86: APL/up_squared kconfig cleanup

The addition of a timer driver made a messy situation worse.  Move
board-level configuration like clock rates and dividers into the board
and don't try to default it in the soc.  Make it clear which kconfig
goes with which driver.  Likewise don't try to do driver selection in
the soc, the board (or app) is in a better position to choose.

Also clean up and better unify the up_squared 32/64 bit settings.
Really only CONFIG_BOARD_NAME needs to care about the difference
between these devices.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>