ANDROID: Add EXPORT_SYMBOL_GPL for dma_heap_get_name

Upstream has no modules that use it, but in common
we system/cma/etc are modular, so we need to export
the new dma_heap_get_name() symbol

Signed-off-by: John Stultz <john.stultz@linaro.org>
Bug: 167709539
Change-Id: I25d77467742ea9c309c909874e0f1e9adf8a64af
Signed-off-by: Hridya Valsaraju <hridya@google.com>
(cherry picked from commit f8c585821898ea87d51dcd520eb3c3889f1bc3ab)
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>