bug in analogout_write_u16() for nucleo F446RE

[manitou48]

My DAC test program worked on LPC1768 and K64F but not on F446RE. DAC write() API says value is 16 bits, and the working platforms shift the value to the proper DAC resolution, but in
mbed/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/analogout_api.c
the DAC value is clipped instead of shifted

The same problem looks to be in
targets/hal/TARGET_STM/TARGET_STM32F7/analogout_api.c
targets/hal/TARGET_STM/TARGET_STM32F3XX/analogout_api.c

Also, analogout_read_u16() in those .c files also aren't shifting the read value into a 16-bit value ...

[0xc0170]

Should be resolved, please verify

[manitou48]

Yep, fixes my problem on F446RE. thanks