usb: host: fix a typo in ehci.h

Change "ehci_hq" to "ehci_qh" in this comment.

Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Link: https://lore.kernel.org/r/20221128081306.2772729-1-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>