ARM: rpi: fix 64-bit CONFIG_SYS_TEXT_BASE

The Pi firmware has changed the default "kernel" load address for 64-bit
mode. The authors have confirmed that this is a deliberate and long-term
change. Adapt U-Boot to the new value.
Signed-off-by: NStephen Warren <swarren@wwwdotorg.org>

include/configs/rpi.h

@@ -48,7 +48,11 @@
 /* Memory layout */
 #define CONFIG_NR_DRAM_BANKS		1
 #define CONFIG_SYS_SDRAM_BASE		0x00000000
+#ifdef CONFIG_ARM64
+#define CONFIG_SYS_TEXT_BASE		0x00080000
+#else
 #define CONFIG_SYS_TEXT_BASE		0x00008000
+#endif
 #define CONFIG_SYS_UBOOT_BASE		CONFIG_SYS_TEXT_BASE
 /*
  * The board really has 256M. However, the VC (VideoCore co-processor) shares