usb: f_qdss: Remove QDSS read functionality as not in use

Removing the APIs related to ctrl_read since those are
not used by any client of f_qdss.

Change-Id: Idf7f1ffd8afe8a72f83e036a7986d35f2f71bea8
Signed-off-by: Udipto Goswami <ugoswami@codeaurora.org>