diag: dci: Rectify updation of peripheral status

Currently, whenever a peripheral is going down, diag
driver is not updating the peripheral status correctly
which leads to wrong result. This patch fixes this issue.

Change-Id: I59065cff4b1a1521d321422e427762bd2661be12
Signed-off-by: Mohit Aggarwal <maggarwa@codeaurora.org>