diag: Return proper value in error case

Presently for error cases return value is improperly updated.
Proper handling is added in error cases to maintain proper return
value.

Change-Id: I771124b8a1eaa29a2eca246cd8c1457309745a85
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>
1 file changed