usb:g_dnl:f_thor: remove memset before memcpy

usb:g_dnl:f_thor: remove memset before memcpy

since ALLOC_CACHE_ALIGN_BUFFER defines a pointer and not a
buffer, the memset with sizeof(rqt) likely does something else
then intended. Since there is a memcpy directly after it with
the full size, drop the memset completely.

Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>