ARM: dts: dra7 clock data

This patch creates a unique node for each clock in the DRA7 power,
reset and clock manager (PRCM).

TODO: apll_pcie clock node is still a dummy in this version, and
proper support for the APLL should be added.

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