bus: ti-sysc: Make omap_hwmod_sysc_fields into sysc_regbits platform data

We want to be able to configure hwmod sysc data from ti-sysc driver using
platform data callbacks. So let's make struct omap_hwmod_sysc_fields into
struct sysc_data and have it available for both ti-sysc driver and hwmod
code.

Note that we can make it use s8 instead of u8 as the hwmod code uses the
feature flags to check for this field. However, for ti-sysc we can use
-ENODEV to indicate a feature is not supported in the hardware and can
simplify the code that way.

And let's add also emufree_shift as the dts files will be describing the
hardware for the SYSCONFIG register capbilities mask.

Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>