drivers: rmnet_shs: Move PS ind dereg up

QMI rmnet indications are deregistered after wq is cleanup
during shs_exit. This leaves a window where after the shs wq
is cleaned-up that it can be potentially used.

This change moves the qmi_rmnet deregistration before the wq
cleanup removing that window.

CRs-Fixed: 2427399
Change-Id: I979cdc65ea69ee4ec6097fb6d67508ab4253891a
Acked-by: Raul Martinez <mraul@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>