gpu: ion: support begin/end and kmap/kunmap dma_buf ops

These ops were added in the 3.4 kernel.  This patch adds support
for them to ion.  Previous ion_map/unmap_kernel api is also
retained in addition to this new api.

Signed-off-by: Rebecca Schultz Zavin <rebecca@android.com>
[jstultz: modified patch to apply to staging directory]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>