soundwire: intel: remove useless readl

Cppcheck complains:

drivers/soundwire/intel.c:564:15: style: Variable 'link_control' is
assigned a value that is never used. [unreadVariable]
 link_control = intel_readl(shim, SDW_SHIM_LCTL);

This looks like a leftover from a previous version, remove.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20210302091122.13952-9-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>