usb: host: xhci: fix ep context print mismatch in debugfs

usb: host: xhci: fix ep context print mismatch in debugfs

dci is 0 based and xhci_get_ep_ctx() will do ep index increment to get
the ep context.

[rename dci to ep_index -Mathias]
Cc: stable <stable@vger.kernel.org> # v4.15+
Fixes: a191edfed15e ("usb: xhci: Add debugfs interface for xHCI driver")
Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200821091549.20556-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>