Add AT32F435 I2C support

[SteveCEvans]

Tested on a REVO with STM32F405 swapped for an AT32F435.

Note BARO=MS5611, MAG=HMC5883 in the below.

# status
MCU AT32F435 Clock=288MHz, Vref=0.34V, Core temp=9degC
Stack size: 2048, Stack address: 0x2002fff0
Configuration: CONFIGURED, size: 3230, max available: 16384
Devices detected: SPI:1, I2C:1
Gyros detected: gyro 1 locked dma
GYRO=MPU6000, ACC=MPU6000, BARO=MS5611, MAG=HMC5883
System Uptime: 10 seconds, Current Time: 2023-02-27T00:23:49.306+00:00
CPU:22%, cycle time: 125, GYRO rate: 8000, RX rate: 15, System rate: 9
Voltage: 0 * 0.01V (0S battery - NOT PRESENT)
I2C Errors: 0
Arming disable flags: RXLOSS CLI MSP MOTOR_PROTO

[blckmn]

AUTOMERGE: (FAIL)

• github identifies PR as mergeable -> PASS
• assigned to a milestone -> PASS
• cooling off period lapsed -> PASS
• commit count less or equal to three -> PASS
• Don't merge label NOT found -> PASS
• at least one RN: label found -> PASS
• Tested label found -> FAIL
• assigned to an approver -> PASS
• approver count at least three -> PASS

[github-actions]

Do you want to test this code? Here you have an automated build:
Assets
WARNING: It may be unstable. Use only for testing! See: https://www.youtube.com/watch?v=I1uN9CN30gw for instructions for unified targets!