qtnfmac: drop redundant data copy in control path

Command responses and events from the firmware are copied twice in
control path: at first in shm core (qtnf_shm_handle_new_data) and
then in pcie bus drivers (qtnf_pcie_control_rx_callback). There
is no need to copy this data twice, it can be done only once
in rx callbacks.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>