qemu_img_negative: Hotfix

Add the missing LF at the end of the cfg file.
Signed-off-by: NXu Han <xuhan@redhat.com>

qemu/tests/cfg/qemu_img_negative.cfg

@@ -28,4 +28,4 @@
                     #Please update portal_ip, initiator and target params based on your test env
                     portal_ip = 127.0.0.1
                     initiator = "iqn.2010-07.com.example:my_initiator"
-                    target = "iqn.2001-05.com.mytarget:0-0a0000-000000000-0000000000000000-my-target"
\ No newline at end of file
+                    target = "iqn.2001-05.com.mytarget:0-0a0000-000000000-0000000000000000-my-target"