[stm32] Fix interrupt loop for uart with tx buffer but no rx buffer

The RXNE interrupt was also enabled if only tx was buffered. The
controller gets stuck in an endless loop because the flag is never
acknowledged in the ISR.

Author: chris-durand

src/modm/platform/uart/stm32/uart.hpp.in

@@ -70,6 +70,8 @@ public:
 		{{ hal }}::initialize<SystemClock, baudrate, tolerance>(parity, length);
 %% if buffered
 		{{ hal }}::enableInterruptVector(true, 12);
+%% endif
+%% if options["buffer.rx"]
 		{{ hal }}::enableInterrupt(Interrupt::RxNotEmpty);
 %% endif
 		{{ hal }}::setTransmitterEnable(true);