Following the file renaming to use the "usb_dwc" prefix, this commit
updates the symbol names of those files to use the "usb_dwc" as well.
Some LL functions were also renamed so that the register name is
mentioned.
This commit adds support for using the RTC I2C peripheral on the ULP
RISC-V core for esp32s2 and esp32s3. It also adds an example to demonstrate the
usage of the RTC I2C peripheral.
This commit also modifies the rtc_i2c register structure files to enable
the use of bitfields in the ULP RISC-V RTC I2C driver.
