nimble/phy/cmac: Fix setting TX power level

TX power is now configured using ble_ll_tx_power_set (instead of
ble_phy_tx_power_set) which uses ble_phy_tx_power_round to calculate
proper TX power level.

This adds missing implementation for that function in CMAC PHY driver so
power level can be properly set.

nimble/drivers/dialog_cmac/src/ble_phy.c

@@ -1655,26 +1655,46 @@ ble_phy_encrypt_disable(void)
 }
 #endif
 
+static int8_t
+phy_txpower_round(int8_t dbm)
+{
+ static const int8_t supported_pwr_levels[] = {-18, -12, -8, -6, -3, -2,
+ -1, 0, 1, 2, 3, 4, 5, 6 };
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(supported_pwr_levels); i++) {
+ if (dbm <= supported_pwr_levels[i]) {
+ dbm = supported_pwr_levels[i];
+ break;
+ }
+ }
+
+ if (i == ARRAY_SIZE(supported_pwr_levels)) {
+ dbm = supported_pwr_levels[ARRAY_SIZE(supported_pwr_levels) - 1];
+ }
+
+ return dbm;
+}
+
 int
 ble_phy_tx_power_set(int dbm)
 {
 #if MYNEWT_VAL(CMAC_DEBUG_DATA_ENABLE)
  if (g_cmac_shm_debugdata.tx_power_ovr_enable) {
- ble_rf_set_tx_power(g_cmac_shm_debugdata.tx_power_ovr);
- } else {
- ble_rf_set_tx_power(dbm);
+ dbm = g_cmac_shm_debugdata.tx_power_ovr;
  }
-#else
- ble_rf_set_tx_power(dbm);
 #endif
 
+ dbm = phy_txpower_round(dbm);
+ ble_rf_set_tx_power(dbm);
+
  return 0;
 }
 
 int
 ble_phy_tx_power_round(int dbm)
 {
- return 0;
+ return phy_txpower_round(dbm);
 }
 
 int