When a register patch is registered the reg_sequence is copied but the
memory allocated is never freed. Add a kfree in regmap_exit to clean it
up.

Fixes: 22f0d90a ("regmap: Support register patch sets")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20200617152129.19655-1-ckeepax@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>