reading ADC channel : sometimes incorrect readings or old readings

[paulvha]

Error 2 description
sometimes incorrect readings when reading ADC channel

Reproduce
no solid reproduction process, but happening intermittent

root cause
Interrupt reset mask is not initialized before being used
by calling am_hal_adc_interrupt_clear()

Solution
Initialize the interrupt reset mask with 0xff to reset all interrupts

########### in ap3_analog.cpp ################

**************routine analogRead(uint8_t pinNumber) ******************
in the top:

change:
uint32_t ui32IntMask;

To :
uint32_t ui32IntMask = 0xff;

[oclyke]

@paulvha I added a commit to the existing PR for ADC order (#135) that should help with this.