dma-buf/dma-resv: Stop leaking on krealloc() failure

Currently dma_resv_get_fences() will leak the previously
allocated array if the fence iteration got restarted and
the krealloc_array() fails.

Free the old array by hand, and make sure we still clear
the returned *fences so the caller won't end up accessing
freed memory. Some (but not all) of the callers of
dma_resv_get_fences() seem to still trawl through the
array even when dma_resv_get_fences() failed. And let's
zero out *num_fences as well for good measure.

Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Fixes: d3c80698

 ("dma-buf: use new iterator in dma_resv_get_fences v3")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20230713194745.1751-1-ville.syrjala@linux.intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>