misc: fastrpc: take into account of overlapping buffers

Argument buffers that are passed could be derived from a big buffer,
and some of the arguments buffers could overlap each other.
Take care of such instanaces.

This is optimization that DSP expects while sending buffers
which overlap. So make the DSP happy doing it.

Without which DSP seems to crash.

Fixes: c68cfb71 ("misc: fastrpc: Add support for context Invoke method")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>