CA-78558: Fix marking of VIFs as disconnected.

Previously the disconnect flag as determined by the VIF's locking mode
overwrote the disconnect flag as determined by the VIF's carrier field.

After this patch, the disconnect flag is set if the VIF's carrier field
is false, OR if the the VIF is disabled.

Signed-off-by: John Else <john.else@citrix.com>
Apply De Morgan's law for readability.

Signed-off-by: John Else <john.else@citrix.com>
Merge pull request #1088 from jeromemaloberti/CA-78558-clearwater

CLEARWATER: CA-78558: Fix marking of VIFs as disconnected.