msm: kgsl: Remove lowest power level

The lowest power level does not correspond to significant
power savings as the whole system doesn't drop to SVS
voltage.  Performace is improved without this level for
serialized test cases.

Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>
(cherry picked from commit c8404a799a26f0744d3965822160c7b05b8d33d7)

Change-Id: Ie349451ffcd82f159eb4d25ad0b986b38f817ede
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>