staging: rtl8723au: pass the cmd parm buffer directly to the cmd handler

commit 0348dc74 ensured that the parm
buffer passed to the cmd handlers is not being over-written. Hence
there is no need to make a copy of the parm buffer just to pass it
into the cmd handler.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>