Add the readAction element to the SVD files for the corresponding registers

[AndreySmirnov81]

This is necessary in order to

For example, for STM32F103 add readAction (modifyExternal) element for registers ADC_DR, USART_DR, TIMx_CCRy.

1. Reading the ADC_DR register clear the EOC bit of the ADC_SR register .
2. Reading the USART_DR register clear the RXNE bit of the USART_SR register .
3. Reading the TIMx_CCRy register clear the CCyIF bit of the TIMx_SR register, where y is 1, 2, 3, 4.
4. The UDR bit is cleared by a read operation on the SPI_SR register