Remove cdc_ether module from factory install shim

(Hack for factory-spring-4262.B branch only; don't merge to ToT)

For factory install/reset shim, we assume ethernet interface to be eth0.
This, however, is not true when eth0 is occupied by other device. In our
case, cdc_ether is occupying eth0. Since cdc_ether is not needed for
factory install/reset, let's remove it to work around this.

BUG=None
TEST=Check 'ifconfig'

Change-Id: I9b8ed88407ccb21db97e9bfcb9ff3ab7d6d840c0
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/172971
Reviewed-by: Rong Chang <rongchang@chromium.org>
diff --git a/common.sh b/common.sh
index 4573f3b..5fd6e05 100644
--- a/common.sh
+++ b/common.sh
@@ -454,6 +454,7 @@
 # Mask for factory install shim (build_image factory_install)
 FACTORY_SHIM_INSTALL_MASK="
   ${DEFAULT_INSTALL_MASK}
+  /lib/modules/3.4.0/kernel/drivers/net/usb/cdc_ether.ko
   /opt/[^g]*
   /opt/google/chrome
   /opt/google/o3d