spi: uapi: spidev: Use TABs for alignment

The UAPI <linux/spi/spidev.h> uses TABs for alignment.
Convert the recently introduced spaces to TABs to restore consistency.

Fixes: 7bb64402 ("spi: tools: Add macro definitions to fix build errors")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20200613073755.15906-1-geert+renesas@glider.beSigned-off-by: Mark Brown <broonie@kernel.org>