rmnet_shs: avoid setting gso info for single segments

Avoid setting the gso info when there is only one segment in
an SKB.

Change-Id: I666fac9500caef5fb9b82b7678df533de9213663
Acked-by: Ryan Chapman <rchapman@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>