clk: ti: add clkctrl data dra7 sgx

This is similar to what we have for omap5 except the gpu_cm address is
different, the mux clocks have one more source option, and there's no
divider clock.

Note that because of the current dts node name dependency for mapping to
clock domain, we must still use "gpu-clkctrl@" naming instead of generic
"clock@" naming for the node. And because of this, it's probably best to
apply the dts node addition together along with the other clock changes.

For accessing the GPU, we also need to configure the interconnect target
module for GPU similar to what we have for omap5, I'll send that change
separately.

Cc: Benoit Parrot <bparrot@ti.com>
Cc: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Robert Nelson <robertcnelson@gmail.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Tero Kristo <t-kristo@ti.com>