spi: mediatek: remove spi_master_put in mtk_spi_remove()

The call to spi_master_put() in mtk_spi_remove() is redundant since
the master is registered using devm_spi_register_master() and no
reference hold by using spi_master_get() in mtk_spi_remove().

This is detected by Coccinelle semantic patch.

Signed-off-by: Wei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>