usb: gadget: f_gps: Clear is_suspended flag on disable

In cases where host resets the function after suspend,
the resume is never called. In this case the is_suspended
flag is never cleared and if remote wakeup is not enabled
the function driver would never queue any response available
notifications.
Fix this by clearing the is_suspended flag on disable.

CRs-Fixed: 2128747
Change-Id: I9e627756009a53eba987b669acab7de004e347a0
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>