ARM: OMAP2+: Fix overwriting of clkctrl and modulemode values

We are currently overwiting the hwmod clkctrl registers if we
configure a clock ctrl clock from device tree.

While this does not expose any bugs except for kernel coders
when debugging things, it should be fixed for correctness.
It is now impossible to use the hwmod data for checking the
clkctrl register values after booting for debugging or
generating dts data from hwmod data.

Let's fix the issue by adding a helper to detect if clkctrl
clock is configured.

Cc: Lokesh Vutla <lokeshvutla@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>