libpayload: Reduce error output from EHCI

Stalled transfers are not fatal, so don't spew on the console on every
tiny failure.

Change-Id: I175c1e83a6af09c1abbd43d045ed6dbf0c79f871
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/1899
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Tested-by: build bot (Jenkins)

payloads/libpayload/drivers/usb/ehci.c

@@ -211,7 +211,7 @@ static int wait_for_tds(qtd_t *head)
 			return 1;
 		}
 		if (cur->token & QTD_HALTED) {
-			printf("ERROR with packet\n");
+			usb_debug("ERROR with packet\n");
 			dump_td(virt_to_phys(cur));
 			usb_debug("-----------------\n");
 			return 1;