thermosphere: major refactor of memory map

- use recursive stage 1 page table (thanks @fincs for this idea)
- NULL now unmapped
- no identity mapping
- image + GICv2 now mapped at the same address for every platform
- tempbss mapped just after "real" bss, can now steal unused mem from
the latter
- no hardcoded VAs for other MMIO devices
- tegra: remove timers, use the generic timer instead

thermosphere/src/platform/qemu/uart.c

@@ -28,16 +28,23 @@
 
 //115200
 
+static uintptr_t g_uartRegBase;
+
 static inline volatile PL011UartRegisters *uartGetRegisters(UartDevice dev)
 {
     switch (dev) {
         case UART_A:
-            return (volatile PL011UartRegisters *)0x09000000;
+            return (volatile PL011UartRegisters *)g_uartRegBase;
         default:
             return NULL;
     }
 }
 
+void uartSetRegisterBase(uintptr_t regBase)
+{
+    g_uartRegBase = regBase;
+}
+
 void uartInit(UartDevice dev, u32 baudRate, u32 flags)
 {
     /* The TRM (DDI0183) reads: