ion: msm: Remove unnecessary free when destroying an ION buffer

When an ION buffer is destroyed, the dma-buf release path will
try to free the exporter name field in the dma-buf. However,
this is not needed, as the field is not populated with
dynamically allocated memory. Thus, remove it.

Change-Id: Ieda30c2130d80ef3e6016e1c574f0524fce14fcc
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>