spi: altera: Fix memory leak on error path

Release master that have been previously allocated if the number of
chipselect is invalid.

Fixes: 8e04187c ("spi: altera: add SPI core parameters support via platform data.")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20210120082635.49304-1-bianpan2016@163.com


Signed-off-by: Mark Brown <broonie@kernel.org>