Revert "ANDROID: Add EXPORT_SYMBOL_GPL for dma_heap_get_name"

This reverts commit cad346da.

This is no longer needed as upstream is exporting this symbol in commit
a6ccb03f ("dma-buf: dma-heap: export declared functions").

Bug: 167709539
Cc: John Stultz <jstultz@google.com>
Cc: T.J. Mercier <tjmercier@google.com>
Change-Id: I3060794e44e8e3e5368c04982802e8d7c01cdd8e
Signed-off-by: Carlos Llamas <cmllamas@google.com>