USB: ehci-hub: Remove redundant ehci->debug check

No need to check ehci->debug twice.

Found-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>