Revert "init: Fix serial number display for semc msm7x30 devices"

This is properly fixed in kernel now. Get rid of this device-specific code.

This reverts commit 5ac7417f81ed6646e0132991095e8f1fd974abaa.

Change-Id: Id81062d3268de6dd021ad90a56480133c487aa62
(cherry picked from commit a118755616aa075833430c45478d80ca67e134a3)