exo/meso/fusee: support dynamic control of log port/baud rate

libraries/libmesosphere/include/mesosphere/board/nintendo/nx/kern_k_system_control.hpp

@@ -30,6 +30,7 @@ namespace ams::kern::board::nintendo::nx {
                     static size_t GetApplicationPoolSize();
                     static size_t GetAppletPoolSize();
                     static size_t GetMinimumNonSecureSystemPoolSize();
+                    static u8 GetDebugLogUartPort();
 
                     /* Randomness. */
                     static void GenerateRandomBytes(void *dst, size_t size);

libraries/libmesosphere/include/mesosphere/kern_debug_log.hpp

@@ -40,7 +40,7 @@ namespace ams::kern {
 #ifndef MESOSPHERE_DEBUG_LOG_SELECTED
 
     #ifdef ATMOSPHERE_BOARD_NINTENDO_NX
-        #define MESOSPHERE_DEBUG_LOG_USE_UART_A
+        #define MESOSPHERE_DEBUG_LOG_USE_UART
     #else
         #error "Unknown board for Default Debug Log Source"
     #endif