Although we have hp t410 booting, I noticed that dm814x-evm does not boot
after I got one. This is because we don't have the clocks yet configured
properly. Let's start configuring proper clocks starting with the system
timers and clocks that work with existing mux and divider clock drivers.

Note that the oscillator speed register is different from am335x, dm814x
has only one bit that shows the BTMODE[6] at CONTROL_STATUS[21].

Also note that this only gets the system timers working with the defined
clocks. The PLL clocks are still missing and and the devices may or may
not work depending on what the bootloader has enabled.
Signed-off-by: Tony Lindgren <tony@atomide.com>