spi: davinci: Fix use-after-free on unbind

davinci_spi_remove() accesses the driver's private data after it's been
freed with spi_master_put().

Fix by moving the spi_master_put() to the end of the function.

Fixes: fe5fd254 ("spi: davinci: Use dma_request_chan() for requesting DMA channel")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: <stable@vger.kernel.org> # v4.7+
Link: https://lore.kernel.org/r/412f7eb1cf8990e0a3a2153f4c577298deab623e.1607286887.git.lukas@wunner.de


Signed-off-by: Mark Brown <broonie@kernel.org>