USB: kobil_sct: Remove unused transfer buffer allocs

Commit 90419cfc,
"USB: kobil_sct: fix control requests without data stage", removed
the bogus data buffer arguments, but still allocate transfer
buffers which are not used.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Johan Hovold <johan@kernel.org>