regulator: Split up _regulator_get()

regulator: Split up _regulator_get()

_regulator_get() contains a lot of common code doing checks prior to the
regulator lookup and housekeeping work after the lookup. Almost all the
code could be shared with a OF-specific variant of _regulator_get().

Split out the common parts so that they can be reused. The OF-specific
version of _regulator_get() will be added in a subsequent patch.
No functional changes were made.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20240911072751.365361-4-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>