staging: r8188eu: write only path a registers in rtw_dbg_port

Commit 3b011b09 ("staging: r8188eu: limit rf register writes to
path a") limited the rtw_wx_write_rf function to write only rf registers
for path a.

The private ioctl 0x0B invokes the rtw_dbg_port function. This ioctl
can also be used for writing rf registers. We should limit these register
writes to rf path a as well.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220212161737.381841-3-martin@kaiser.cx


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>