#402 STM32L43x Option Byte read/write error

[Arney Sieling]

stm32l4x option_read and stm32l4x option_write uses incorrect base address (or at least for the STM32L43x family of MCUs, I did not verify the Option Byte addresses of other STM32L4x MCUs).

The base address currently used by OpenOCD for STM32L4x MCUs is 0x40022000, this should be 0x1FFF7800, and as a result any calls to stm32l4x option_read and stm32l4x option_write fails to read/write the option bytes of an STM32L43x MCU.