sandbox, x86: select DM_KEYBOARD instead of default y entry

Once we migrate to DM-based drivers, we cannot go back to legacy
ones, i.e. config options like DM_* are not user-configurable.

Make SANDBOX and X86 select DM_KEYBOARD like other platforms do.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/Kconfig b/arch/Kconfig
index d718a68..ffc7b45 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -62,6 +62,7 @@
 	bool "Sandbox"
 	select SUPPORT_OF_CONTROL
 	select DM
+	select DM_KEYBOARD
 	select DM_SPI_FLASH
 	select DM_SERIAL
 	select DM_I2C
@@ -83,6 +84,7 @@
 	select HAVE_PRIVATE_LIBGCC
 	select SUPPORT_OF_CONTROL
 	select DM
+	select DM_KEYBOARD
 	select DM_SERIAL
 	select DM_GPIO
 	select DM_SPI