ARM: dts: msm: reduce the minimum vote on ahb bus

This change ensures that voltage on CNOC does not scale to a higher
voltage corner than intended. Display driver only intends to enable
the CNOC on power collapse restore. When display really needs higher
performance i.e. at first commit it votes for the real bandwidth
required.

Change-Id: Ib9d9786aed0315fe0457ccb6dbcb73a5a8ad2917