host: Give DCDC converter time to settle when we set PA output power.

host/umtrx_impl.cpp

@@ -697,6 +697,9 @@ double umtrx_impl::set_pa_power(double power, const std::string &which)
     // Set the value
     set_pa_dcdc_r(dcdc_val);
 
+    // Wait for the DCDC converter output to settle before we read it back
+    boost::this_thread::sleep(boost::posix_time::milliseconds(100));
+
     // Check what power do we actually have by reading the DCDC voltage
     // and converting it to the PA power
     double v_actual = read_dc_v("DCOUT").to_real();