RFSPOL_SHIFT
msp_config->rx_fsync_pol ^= 1 << RFSPOL_SHIFT;
prot_desc->rx_fsync_pol = MSP_FSYNC_POL_ACT_HI << RFSPOL_SHIFT;
prot_desc->rx_fsync_pol = MSP_FSYNC_POL_ACT_LO << RFSPOL_SHIFT;