modbus_get_float_dcba - get a float value from 2 registers in DCBA byte order
float modbus_get_float_dcba(const uint16_t *src);
The modbus_get_float_dcba() function shall get a float from 4 bytes in
inverted Modbus format (DCBA order instead of ABCD). The src
array must be a
pointer on two 16 bits values, for example, if the first word is set to 0x47F1
and the second to 0x2000, the float value will be read as 123456.0.
The function shall return a float.