spi: zynq-qspi: Keep the naming consistent across the driver

spi: zynq-qspi: Keep the naming consistent across the driver

In this driver (and also in a lot of other drivers in drivers/spi/),
the spi_controller structure is sometimes referred as 'ctlr' and
sometimes as 'ctrl'. Grepping there shows that 'ctlr' seems to be more
common so keep the naming consistent in this driver and s/ctrl/ctlr/.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20191108105920.19014-3-miquel.raynal@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>