Fixed pin ownership checks for I2C.

[mikeller]

Fixes #9806.

This fixes the problem that currently, IOInit() does not check if a pin is already used (i.e. has an owner assigned) before setting the owner. This leads to cases where a pin is successfully assigned and a pin function started, but then the pin gets re-assigned to a different function, leaving artefacts:

Setup:

# resource

[...]

resource MOTOR 4 C09

[...]

resource I2C_SDA 3 C09

[...]

Before:

# resource show all

[...]

C09: I2C_SDA 3

[...]

Currently active Timers:
-----------------------
TIM1: FREE
TIM2: FREE
TIM3:
    CH1: MOTOR 1
TIM4: FREE
TIM5: FREE
TIM6: FREE
TIM7: FREE
TIM8:
    CH2: MOTOR 2
    CH3: MOTOR 3
    CH4: MOTOR 4

Currently active DMA:
--------------------
DMA1 Stream 0: FREE
DMA1 Stream 1: FREE
DMA1 Stream 2: TIMUP 3
DMA1 Stream 3: FREE
DMA1 Stream 4: FREE
DMA1 Stream 5: FREE
DMA1 Stream 6: FREE
DMA1 Stream 7: FREE
DMA2 Stream 0: ADC 1
DMA2 Stream 1: TIMUP 8
DMA2 Stream 2: FREE
DMA2 Stream 3: FREE
DMA2 Stream 4: FREE
DMA2 Stream 5: FREE
DMA2 Stream 6: FREE
DMA2 Stream 7: FREE

After:

# resource show all

[...]

C09: MOTOR 4

[...]

Currently active Timers:
-----------------------
TIM1: FREE
TIM2: FREE
TIM3:
    CH1: MOTOR 1
TIM4: FREE
TIM5: FREE
TIM6: FREE
TIM7: FREE
TIM8:
    CH2: MOTOR 2
    CH3: MOTOR 3
    CH4: MOTOR 4

Currently active DMA:
--------------------
DMA1 Stream 0: FREE
DMA1 Stream 1: FREE
DMA1 Stream 2: TIMUP 3
DMA1 Stream 3: FREE
DMA1 Stream 4: FREE
DMA1 Stream 5: FREE
DMA1 Stream 6: FREE
DMA1 Stream 7: FREE
DMA2 Stream 0: ADC 1
DMA2 Stream 1: TIMUP 8
DMA2 Stream 2: FREE
DMA2 Stream 3: FREE
DMA2 Stream 4: FREE
DMA2 Stream 5: FREE
DMA2 Stream 6: FREE
DMA2 Stream 7: FREE

This is just one fix to solve a problem that is currently breaking configurations for users. A comprehensive switch to replace IOInit() with functionality that checks resource ownership is needed, and is currently work in progress, to be added after 4.2 has been released.

Also removing a duplicate RCC_ClockCmd() line.

Test firmware:

betaflight_4.2.0_STM32F745_37209b4826.zip
betaflight_4.2.0_STM32F7X2_37209b4826.zip
betaflight_4.2.0_STM32F411_37209b4826.zip
betaflight_4.2.0_STM32F405_37209b4826.zip

(installation instructions: youtu.be/I1uN9CN30gw)