f_rmnet: Notify USB is disconnected to QTI when performing bus suspend

USB RMNET function has data path (BAM2BAM IPA) and ctrl path (QTI) to
talk with modem. Current code tears down data path but it keeps ctrl
path. USB bus suspend with remote wakeup disable case, it is being
observed that USB controller is coming out of LPM due to modem is trying
to send control packet through QTI with USB interrupt notification which
results into remote wakeup functionality being initiated due to host is
bus suspended. Fix this issue by notifying QTI that USB is disconnected
and connected when performing USB bus suspend and resume respectively with
remote wakeup disable case.

CRs-Fixed: 761133
Change-Id: Icb24cb3d3fee2708deb8a44e3a7714a4d2755523
Signed-off-by: Mayank Rana <mrana@codeaurora.org>