dmaengine: ti: unexport filter functions

dmaengine: ti: unexport filter functions

The two filter functions are now marked static, but still exported,
which triggers a coming build-time check:

WARNING: "omap_dma_filter_fn" [vmlinux] is a static EXPORT_SYMBOL_GPL
WARNING: "edma_filter_fn" [vmlinux] is a static EXPORT_SYMBOL

Remove the unneeded exports as well, as originally intended.

Fixes: feeaeae404f6 ("dmaengine: omap-dma: make omap_dma_filter_fn private")
Fixes: 444d0cea481c ("dmaengine: edma: make edma_filter_fn private")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190812101155.997721-1-arnd@arndb.de
Signed-off-by: Vinod Koul <vkoul@kernel.org>