dt-bindings: regulator: pf8x00: Remove restrictions for regulator-name

Following commit b0de7fa7
("regulator: pca9450: Remove restrictions for regulator-name") to remove
the constraints on the regulator-name to allow using arbitrary and
descriptive names for the regulators.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20230328060032.1983381-1-peng.fan@oss.nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>