davinci: Add base address and timer flexibility

The davinci timer code currently hardcodes the timer register
base addresses, the timer irq numbers, and the timers to use
for clock events and clocksource.  This won't work for some
a new SoC so put those values into the soc_info structure
and set them up in the SoC-specific files.

Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>