sandbox: Enable bitrev library build

Imply CONFIG_BITREVERSE for Sandbox.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/Kconfig b/arch/Kconfig
index bf1b4a9..11900b0 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -78,6 +78,7 @@
 	select LZO
 	select SPI
 	select SUPPORT_OF_CONTROL
+	imply BITREVERSE
 	imply CMD_DM
 	imply CMD_GETTIME
 	imply CMD_HASH