spi: fsl: Kill mpc8xxx_spi_cleanup and convert fsl_espi_setup to use devm_kzalloc

In current code, master->cleanup and master->setup are not set in the same
function. This makes it hard to read and not good for code maintain.
One example is in fsl-spi.c, master->cleanup is overrided in mpc8xxx_spi_probe()
which leads to a memory leak.

This patch removes mpc8xxx_spi_cleanup() and converts fsl_espi_setup to use
devm_kzalloc so we don't need to take care of freeing memory.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>