usb: gadget: ECM: Add super speed descriptors for qc_ecm function

This change adds super speed descriptors which is required to get
ECM function to work with SSUSB mode.

CRs-Fixed: 627063
Change-Id: I275a32f6cb957b59bfdf1c5b5377ba6e189efb6d
Signed-off-by: Mayank Rana <mrana@codeaurora.org>