spi: spi-fsl-dspi: Drop extra spi_master_put in device remove function

The call sequence spi_alloc_master/spi_register_master/spi_unregister_master
is complete; it reduces the device reference count to zero, which and results
in device memory being freed. The subsequent call to spi_master_put is
unnecessary and results in an access to free memory. Drop it.

Fixes: 9298bc72 ("spi: spi-fsl-dspi: Remove spi-bitbang")
Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>