[usb] Clear device endpoint halt before resetting host endpoint

[usb] Clear device endpoint halt before resetting host endpoint

Resetting the host endpoint may immediately restart any pending
transfers for that endpoint.  If the device endpoint halt has not yet
been cleared, then this will probably result in a second failed
transfer.

This second failure may be detected within usb_endpoint_reset() while
waiting for usb_clear_feature() to complete.  The endpoint will
subsequently be removed from the list of halted endpoints, causing the
second failure to be effectively ignored and leaving the host endpoint
in a permanently halted state.

Fix by deferring the host endpoint reset until after the device
endpoint is ready to accept new transfers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>