regulator: ti-abb: Add support for interleaved LDO registers

Certain platforms such as DRA7 have quirky memory maps such as:
PRM_ABBLDO_DSPEVE_CTRL	0x4ae07e20
PRM_ABBLDO_IVA_CTRL	0x4ae07e24
other-registers
PRM_ABBLDO_DSPEVE_SETUP	0x4ae07e30
PRM_ABBLDO_IVA_SETUP	0x4ae07e34

These need the address range allocation to be either not reserved OR
unique allocation per register instance or use something like syscon
based solution.

By going with unique allocation per register, we are able to now have
a single compatible driver for all instances on all platforms which
use the IP block.

So, introduce a new "ti,abb-v3" compatible to allow for definitions
where explicit register definitions are provided, while maintaining
backward compatibility of older predefined register offsets provided
by "ti-abb-v1" and "ti-abb-v2".

As part of this change, we rename a few variables to indicate the
appropriate meaning.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>