libpayload udc: add interface to add string descriptors

They're ASCII only, with only one language at a time,
but they should be good enough to report device names and
serial numbers.

BUG=none
BRANCH=none
TEST=with depthcharge CL, check dmesg on the host device

Change-Id: If888e05b2f372f7f0f43fadb108ca7ef4ed3b7c1
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: f0bc4242057d3edc4f4796ebeed2d98d89d60a1d
Original-Change-Id: Ibe42f1b49f412e5482cebb7ebe20f6034352fd12
Original-Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/278300
Original-Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Original-Commit-Queue: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10626
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
diff --git a/payloads/libpayload/drivers/udc/chipidea.c b/payloads/libpayload/drivers/udc/chipidea.c
index 8299a08..16a42e4 100644
--- a/payloads/libpayload/drivers/udc/chipidea.c
+++ b/payloads/libpayload/drivers/udc/chipidea.c
@@ -489,6 +489,7 @@
 
 	ctrl->poll = chipidea_poll;
 	ctrl->add_gadget = udc_add_gadget;
+	ctrl->add_strings = udc_add_strings;
 	ctrl->enqueue_packet = chipidea_enqueue_packet;
 	ctrl->shutdown = chipidea_shutdown;
 	ctrl->set_address = chipidea_set_address;