xtensa: add support for the xtensa processor architecture [2/2]

The Xtensa processor architecture is a configurable, extensible,
and synthesizable 32-bit RISC processor core provided by Tensilica, inc.

This is the second part of the basic architecture port, adding the
'arch/xtensa' directory and a readme file.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
new file mode 100644
index 0000000..bb6a678
--- /dev/null
+++ b/arch/xtensa/Kconfig
@@ -0,0 +1,18 @@
+menu "Xtensa architecture"
+	depends on XTENSA
+
+config SYS_ARCH
+	string
+	default "xtensa"
+
+config SYS_CPU
+	string "Xtensa Core Variant"
+
+choice
+	prompt "Target select"
+
+
+endchoice
+
+
+endmenu