net: rmnet_usb: Add sleep state extended IOCTL

By default HSIC autosuspend is enabled, however it may
introduce additional latency depending on client application
usecase. Add support for sleep state IOCTL to allow the client
to enable/disable the autosuspend as needed.

Change-Id: Ib4e2f9e83f86837e05339689c8735c843483bb3d
Signed-off-by: Azhar Shaikh <azhars@codeaurora.org>