ARM: dts: Don't use legacy clock defines for dra7 clkctrl

Looks like we are still using legacy clock defines for dra7. We want to
stop using these as it prevents dropping the legacy clocks. Note that
this is just a cosmetic fix.

Cc: Tero Kristo <kristo@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>