spidev: Decrease indentation level in spidev_ioctl() SPI_IOC_RD_MODE*

spidev: Decrease indentation level in spidev_ioctl() SPI_IOC_RD_MODE*

Instead of defining a local controller variable inside an indented
block, move the definition to the top of spidev_ioctl() and reuse
it in the SPI_IOC_RD_MODE* and SPI_IOC_WR_MODE* cases.

This drops unneeded indentation and reduces amount of LoCs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20230824162209.2890440-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>