Fix: Standby after regular write cmd

Realized that the normal write command should always drop to standby-I
mode immediately since the FIFO cannot be filled using this method, and
TX will be complete.

RF24.cpp

@@ -455,6 +455,8 @@ bool RF24::write( const void* buf, uint8_t len )
 	//If autoAck is ON, a payload has to be written prior to reading a payload, else write after reading a payload
 	while( ! ( get_status()  & ( _BV(TX_DS) | _BV(MAX_RT) ))) { }
 
+	ce(LOW); //Set the radio back to STANDBY-I mode since we can only fill one buffer at a time using this method, and tx is complete
+
 	uint8_t status = write_register(STATUS,_BV(RX_DR) | _BV(TX_DS) | _BV(MAX_RT) );
 
   //Max retries exceeded