Fix EHCI usb submit timeout and unify with OHCI

Changed both to use a common timeout for URB submission, since they were using
different values and EHCI's was too short.

Also fixed EHCI to actually check if urb submission succeeded, rather than
silently continuing into the weeds.

Change-Id: I7f71499ffaa05187d8e5618db2419e1606007b82

Signed-off-by: Simon Glass <sjg@chromium.org>