Staging: add echo cancelation module

This is used by mISDN and Zaptel drivers.

From: Steve Underwood <steveu@coppice.org>
From: David Rowe <david@rowetel.com>
Cc: Tzafrir Cohen <tzafrir.cohen@xorcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 5741984..93decb8 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -8,3 +8,4 @@
 obj-$(CONFIG_USB_IP_COMMON)	+= usbip/
 obj-$(CONFIG_W35UND)		+= winbond/
 obj-$(CONFIG_PRISM2_USB)	+= wlan-ng/
+obj-$(CONFIG_ECHO)		+= echo/