dt-bindings: clock: Move ti-dra7-atl.h to dt-bindings/clock

dt-bindings: clock: Move ti-dra7-atl.h to dt-bindings/clock

Most of the clock related dt-binding header files are located in
dt-bindings/clock folder. It would be good to keep all the similar
header files at a single location.

Suggested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tero Kristo <t-kristo@ti.com>