ARM: dts: AM35xx: use DT clock data

AM35xx now uses the clock data from device tree. Most of the data is
shared with OMAP3xxx, but as there is some delta, a new base .dtsi
file is also created for the SoC.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>