soc: qcom: socinfo: Implement arch specific machine_name

For device tree's overlay solution, the only model
string for machine name is not sufficient, since
board device tree's model cannot overall present
each soc information. So introduce two properties
"qcom,msm-name" and "qcom,pmic-name" for soc device
tree to add soc specific information name, which can
be merged into machine_name later in kernel setup.

Change-Id: I16b4ad4e203694bfa900eb0b6403690d585e3ddb
Signed-off-by: Maria Yu <aiquny@codeaurora.org>