MAINTAINERS: Add co-maintainer for ARM/Qualcomm Support

Added myself as a co-maintainer.  Updated the files to include the
Qualcomm SoC directory.  Added linux-soc mailing list.

Signed-off-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Kumar Gala <galak@codeaurora.org>