regulator: Use bitfield values for range selectors

Right now the regulator helpers expect raw register values for the range
selectors. This is different from the voltage selectors, which are
normalized as bitfield values. This leads to a bit of confusion. Also,
raw values are harder to copy from datasheets or match up with them,
as datasheets will typically have bitfield values.

Make the helpers expect bitfield values, and convert existing users. The
field in regulator_desc is renamed to |linear_range_selectors_bitfield|.
This is intended to cause drivers added in the same merge window and
out-of-tree drivers using the incorrect variable and values to break,
preventing incorrect values being used on actual hardware and potentially
producing magic smoke.

Also include bitops.h explicitly for ffs(), and reorder the header include
statements. While at it, also replace module.h with export.h, since the
only use is EXPORT_SYMBOL_GPL.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Link: https://lore.kernel.org/r/20230714081408.274567-1-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>

regulator: max77541: Add ADI MAX77541/MAX77540 Regulator Support

Regulator driver for both MAX77541 and MAX77540.
The MAX77541 is a high-efficiency step-down converter
with two 3A switching phases for single-cell Li+ battery
and 5VDC systems.

The MAX77540 is a high-efficiency step-down converter
with two 3A switching phases.

Signed-off-by: Okan Sahin <okan.sahin@analog.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230412111256.40013-3-okan.sahin@analog.com
Signed-off-by: Lee Jones <lee@kernel.org>