diag: Handle mode change commands properly

Currently, if APPS master table is having mode reset command
registration followed by other mode change commands then
APPS driver will not be able to forward mode change commands
to Modem. This patch fixes this issue.

Change-Id: I502e0a9a222d954c16b36df275585df39a84f970
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>