USB: serial: keyspan_pda: use usb_control_msg_recv()

Use the wrapper function usb_control_msg_recv() that accepts stack
variables and remove dma buffers from callers of usb_control_msg().

Signed-off-by: Himadri Pandya <himadrispandya@gmail.com>
Link: https://lore.kernel.org/r/20210801203122.3515-6-himadrispandya@gmail.com


[ johan: simplify write-room error handling further ]
Signed-off-by: Johan Hovold <johan@kernel.org>