regulator: tps6594-regulator: refactor variant descriptions

regulator: tps6594-regulator: refactor variant descriptions

Instead of using conditionals or tri state operators throughout the
.probe() provide a description per variant. This will make it much
easier to add new variants later.

While at it, make the variable naming more consistent.

This patch is only compile-time tested.

Signed-off-by: Michael Walle <mwalle@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20250703113153.2447110-8-mwalle@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>