staging: slicoss: replace memcpy_fromio with memcpy

As per discusion with Lino Sanfilippo, memcpy is the proper way to copy
across dma memory, which also removes sparse warning that triggered
inquiry.

Signed-off-by: Ryan Swan <ryan@ryanswan.com>
Reviewed-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>