On ESP32-S3, USB PHY is clocked from BBPLL,
however if the BBPLL is not used as CPU clock source,
the power management unit can turn it off.
This commit registers USB as BBPLL consumer so it is not turned off.
Closes https://github.com/espressif/esp-idf/issues/15451
Moved USB PHY source and headers from `usb/` to `esp_hw_support/`
to better reflect their hardware-specific nature.
Replaced use of public GPIO driver APIs with internal LL (Low-Level) APIs
for more precise hardware control and alignment with ESP-IDF HAL best practices.
Deleted deprecated PHY helper functions.
Consolidated all SoC-specific declarations under `usb_periph.h`.
BREAKING CHANGE: deprecated USB PHY APIs have been removed; update
callers to use the new interfaces in esp_hw_support/usb_phy.h