driver-DAC8871

fix(esp32): correct SPI mode from 0 to 1 for DAC8871 timing

fix(esp32): replace queue_trans with spi_device_transmit to prevent deadlock

fix: guard against NULL write_16b function pointer in dac8871_set_code

fix(esp32): move initialized flags into arg struct for multi-instance safety

fix: replace bitwise OR on enum with direct return in dac8871_set_code