ion: carveout heap: zero buffers on free, fix memory leak
The carveout heap wasn't zeroing its buffers after use.
Create the sg_table during allocate instead of map_dma, to allow
using the sg_table during free, and call ion_heap_buffer_zero
during free. Also fixes a missing kfree when destroying the
table.
Signed-off-by: Colin Cross <ccross@android.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>