MAINTAINERS: Update the Spreadtrum SoC maintainer

Change my email address, and add more Spreadtrum SC27xx series PMIC
drivers to maintain.

Link: https://lore.kernel.org/r/a48483d13243450ecf3b777d49e741b6367f2c6b.1571881956.git.baolin.wang@linaro.org


Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>