staging: echo: move to drivers/misc/

The code is clean, there are users of it, so it doesn't belong in
staging anymore, move it to drivers/misc/.

Cc: Steve Underwood <steveu@coppice.org>
Cc: David Rowe <david@rowetel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 6cb388e..3816b59 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -526,4 +526,5 @@
 source "drivers/misc/vmw_vmci/Kconfig"
 source "drivers/misc/mic/Kconfig"
 source "drivers/misc/genwqe/Kconfig"
+source "drivers/misc/echo/Kconfig"
 endmenu