spi: spi-fsl-dspi: Use reverse Christmas tree declaration order

This patch puts variable declaration in the reverse order of their
length for cosmetic purposes.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20190818180115.31114-11-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>