regulator: max5970: Fix regulator child node name

Update regulator child node name to lower case i.e., sw0 & sw1 as
descibed in max5970 dt binding.

Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
Link: https://msgid.link/r/20240213145801.2564518-1-naresh.solanki@9elements.com
Signed-off-by: Mark Brown <broonie@kernel.org>