arm: dra7xx: clock: Add the dplls data

A new DPLL DDR is added in DRA7XX socs. Now clocks to
EMIF CD is from DPLL DDR. So DPLL DDR should be locked
before initializing RAM.
Also adding other dpll data which are different from OMAP5 ES2.0.
SYS_CLK running at 20MHz is introduced in DRA7xx socs.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: R Sricharan <r.sricharan@ti.com>
Reviewed-by: Tom Rini <trini@ti.com>