MAINTAINERS: Split Qualcomm SoC and linux-arm-msm entries

The Qualcomm Support entry in MAINTAINERS has served the purpose of both
defining the scope of the Qualcomm support, and to make Qualcomm-related
patches show up on the linux-arm-msm mailing list.

While this continues to serve our needs, it occasionally do create
confusion about the ownership.

Split the entry to clarify which components are maintained under the
qcom-soc tree.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Acked-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240319-maintainer-qcom-split-v1-1-735d975af2c2@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>