regmap: sdw-mbq: use MODULE_LICENSE("GPL")

"GPL v2" is the same as "GPL". It exists for historic reasons.
See Documentation/process/license-rules.rst

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210122070634.12825-8-yung-chuan.liao@linux.intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>