phy: stm32: adopt dev_err_probe for regulators

Change stm32-usbphyc driver to use dev_err_probe(), to benefit of
devices_deferred debugfs in case of probe deferral.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/1635172265-26219-1-git-send-email-fabrice.gasnier@foss.st.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>