arm64: defconfig: enable BST platform support

Enable support for Black Sesame Technologies (BST) platform
in the ARM64 defconfig:
- CONFIG_ARCH_BST: Enable BST SoC platform support

Signed-off-by: Albert Yang <yangzh0906@thundersoft.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: jycs168

arch/arm64/configs/defconfig

@@ -47,6 +47,7 @@ CONFIG_ARCH_BCMBCA=y
 CONFIG_ARCH_BRCMSTB=y
 CONFIG_ARCH_BERLIN=y
 CONFIG_ARCH_BLAIZE=y
+CONFIG_ARCH_BST=y
 CONFIG_ARCH_CIX=y
 CONFIG_ARCH_EXYNOS=y
 CONFIG_ARCH_SPARX5=y