Fix missing return warnings

Firmware/ConfigurationStore.h

@@ -21,7 +21,7 @@ FORCE_INLINE void Config_RetrieveSettings() { Config_ResetDefault(); Config_Prin
 #endif
 
 inline uint8_t calibration_status() { return eeprom_read_byte((uint8_t*)EEPROM_CALIBRATION_STATUS); }
-inline uint8_t calibration_status_store(uint8_t status) { eeprom_update_byte((uint8_t*)EEPROM_CALIBRATION_STATUS, status); }
+inline void calibration_status_store(uint8_t status) { eeprom_update_byte((uint8_t*)EEPROM_CALIBRATION_STATUS, status); }
 inline bool calibration_status_pinda() { return eeprom_read_byte((uint8_t*)EEPROM_CALIBRATION_STATUS_PINDA); }
 
 #endif//CONFIG_STORE_H

Firmware/Marlin_main.cpp

@@ -1873,6 +1873,7 @@ int serial_read_stream() {
         }
 
     }
+	return 0;
 }
 
 #ifdef HOST_KEEPALIVE_FEATURE

Firmware/tmc2130.cpp

@@ -639,6 +639,7 @@ uint8_t tmc2130_tx(uint8_t axis, uint8_t addr, uint32_t wval)
 	TMC2130_SPI_TXRX(wval & 0xff); // LSB
 	tmc2130_cs_high(axis);
 	TMC2130_SPI_LEAVE();
+	return 0;
 }
 
 uint8_t tmc2130_rx(uint8_t axis, uint8_t addr, uint32_t* rval)

Firmware/uart2.c

@@ -45,6 +45,7 @@ uint8_t uart2_rx_clr(void)
 {
 	rbuf_w(uart2_ibuf) = 0;
 	rbuf_r(uart2_ibuf) = 0;
+	return 0;
 }
 
 uint8_t uart2_rx_ok(void)