msm: 8226: add board file support for msm8926

Populate the DT match table with a string for msm8926 so that
the same board files can be used for both targets.

Change-Id: I1ab003c9e98c73b4cb7334c19e63c170ff7d5b9d
Signed-off-by: Syed Rameez Mustafa <rameezmustafa@codeaurora.org>