Move gsv_rdm_data_receive_end` out of anonymous namespace

Relocates `gsv_rdm_data_receive_end` from the anonymous namespace to file scope so it has external linkage while keeping the rest of the DMX/RDM buffer layout unchanged.

Author: vanvught

lib-dmx/src/gd32/dmx.cpp

@@ -189,8 +189,6 @@ volatile dmx::TotalStatistics sv_total_statistics[dmx::config::max::kPorts] ALIG
 
 // DMX RX
 volatile dmx::RxDmxPackets sv_rx_dmx_packets[dmx::config::max::kPorts] ALIGNED;
-// RDM RX
-volatile uint32_t gsv_rdm_data_receive_end[dmx::config::max::kPorts];
 // DMX RDM RX
 volatile dmx::RxData sv_rx_buffer[dmx::config::max::kPorts] ALIGNED;
 // DMX TX
@@ -200,6 +198,9 @@ dmx::DmxTransmit s_dmx_transmit;
 dmx::RdmTxData s_RdmTxBuffer[dmx::config::max::kPorts] ALIGNED SECTION_DMA_BUFFER;
 } // namespace
 
+// RDM RX
+volatile uint32_t gsv_rdm_data_receive_end[dmx::config::max::kPorts];
+
 template <uint32_t kUsartPeripheral>
 void IrqHandlerDmxRdmInput() {
     constexpr auto kPortIndex = GetPortByUart(kUsartPeripheral);