In stm32f7xx_ll_adc.h, from revision 1.8 of HAL (stm32cube_fw_f7_v180.zip), the following register base addresses are defined:
#define VREFINT_CAL_ADDR ((uint16_t*) (0x1FF07A4A))
#define TEMPSENSOR_CAL1_ADDR ((uint16_t*) (0x1FF07A4C))
#define TEMPSENSOR_CAL2_ADDR ((uint16_t*) (0x1FF07A4E))
Those addresses do not correspond to the addresses in the datasheet for STM32F746XX, DocID027590 Rev 4, and do not provide correct data either.
V REFIN_CAL Raw data acquired at temperature of 30 °C V DDA = 3.3 V 0x1FF0 F44A - 0x1FF0 F44B
TS_CAL1 TS ADC raw data acquired at temperature of 30 °C, V DDA = 3.3 V 0x1FF0 F44C - 0x1FF0 F44D
TS_CAL2 TS ADC raw data acquired at temperature of 110 °C, V DDA = 3.3 V 0x1FF0 F44E - 0x1FF0 F44F
Looks like a bug in LL HAL for F7.