USB: EHCI: remove useless test

This patch (as1605) removes a useless test from the EHCI debugfs
code.  There's no point checking whether p.qh is non-NULL; we already
know it is and in any case it gets dereferenced aerlier in the
function.

The useless test was identified by smatch.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>