conf: fixup USB input bus check
This patch fixes the USB input bus check, the bug was introduced by commit 317badb
Signed-off-by: Xiao Feng Ren <renxiaof@linux.vnet.ibm.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>