usb: gadget: qdss: Add support for qdss fs descriptor handling

Currently f_qdss driver does not support full-speed mode. This results
in Chapter 9 USB2 CV Other Speed Configuration Test failures with qdss
composition. Hence add full speed descriptors support in qdss driver.

Change-Id: I1ca4b2f1aba1479661f89497cfd5c5f25369fa8e
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
Signed-off-by: Mayank Rana <mrana@codeaurora.org>