usb: u_ether: Add missing rx_work init

usb: u_ether: Add workqueue as bottom half handler for rx data path

set up a worker for the rx data path but missed a case where
the work_struct needed to be initialized.

This patch adds the missing 'INIT_WORK'.

Change-Id: I2daabd39d35b3e17a3054837282d649d9c78a0aa
Git-Commit: 5df322294fb5d6a1b5beac0549ef37426bdaa1fe
Git-repo: https://source.codeaurora.org/quic/la/kernel/msm-4.9


Signed-off-by: Matthew Moeller <moeller.matt@gmail.com>
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>