dm: tegra: Avoid using arch-specific memcpy() in SPL

The faster functions are not actually available in SPL and the code size
likely isn't worth it. Use the normal memcpy() in SPL.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/configs/tegra-common.h

@@ -118,7 +118,9 @@
 #define CONFIG_SYS_MEMTEST_START	(NV_PA_SDRC_CS0 + 0x600000)
 #define CONFIG_SYS_MEMTEST_END		(CONFIG_SYS_MEMTEST_START + 0x100000)
 
+#ifndef CONFIG_SPL_BUILD
 #define CONFIG_USE_ARCH_MEMCPY
+#endif
 
 /*-----------------------------------------------------------------------
  * Physical Memory Map