build: Use common name for QCOM 7K boards.

This is needed to build QCOM HAL without external modifications. The
device would now have to specify msm7x27 or msm7x30 instead of
specifying the full name.

Patch Set 2: Add msm7x27a into the list.

Change-Id: I25018e397b5aad27fab5244731a574ae86752e17