Fixes TMC compilation error

Marlin/src/feature/tmc_util.cpp

         break;
       case TMC_TPWMTHRS_MMS: {
           uint32_t tpwmthrs_val = st.TPWMTHRS();
-          tpwmthrs_val ? SERIAL_ECHO(12650000UL * st.microsteps() / (256 * tpwmthrs_val * spmm)) : SERIAL_CHAR('-');
+          if (tpwmthrs_val)
+            SERIAL_ECHO(12650000UL * st.microsteps() / (256 * tpwmthrs_val * spmm));
+          else
+           SERIAL_CHAR('-');
         }
         break;
       case TMC_OTPW: serialprintPGM(st.otpw() ? PSTR("true") : PSTR("false")); break;