configs: stm32: enable USB onboard HUB driver

Activate the USB onboard HUB driver, that is used to enable the HUB supply
on STM32MP15 EVAL, DK1 and DK2 boards.
This avoids marking the 3v3 corresponding regulator as always-on.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>