spi/rockchip: remove redundant call to spi_master_put()

The call to spi_master_put() in rockchip_spi_remove() is redundant since
the master is registered using devm_. This patch removes it.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>