mfd: tps65090: Stop caching most registers

Nearly all of the registers in tps65090 combine control bits and
status bits.  Turn off caching of all registers except the select few
that can be cached.

In order to avoid adding more duplicate #defines, we also move some
register offset definitions to the mfd driver (and resolve
inconsistent names).

Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>