rename symbol: CONFIG_TEGRA -> CONFIG_ARCH_TEGRA

Have this symbol follow the pattern of all other such symbols.

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 6f37f75..414b6f3 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -970,7 +970,7 @@
 
 config SPL_RAM_SUPPORT
 	bool "Support booting from RAM"
-	default y if MICROBLAZE || ARCH_SOCFPGA || TEGRA || ARCH_ZYNQ
+	default y if MICROBLAZE || ARCH_SOCFPGA || ARCH_TEGRA || ARCH_ZYNQ
 	help
 	  Enable booting of an image in RAM. The image can be preloaded or
 	  it can be loaded by SPL directly into RAM (e.g. using USB).
@@ -978,7 +978,7 @@
 config SPL_RAM_DEVICE
 	bool "Support booting from preloaded image in RAM"
 	depends on SPL_RAM_SUPPORT
-	default y if MICROBLAZE || ARCH_SOCFPGA || TEGRA || ARCH_ZYNQ
+	default y if MICROBLAZE || ARCH_SOCFPGA || ARCH_TEGRA || ARCH_ZYNQ
 	help
 	  Enable booting of an image already loaded in RAM. The image has to
 	  be already in memory when SPL takes over, e.g. loaded by the boot