clk: msm: clock: Vote on MX rail on behalf of MM PLLs on MSMCOBALT

The multimedia PLLs are all in the MX domain on MSMCOBALT. Replace
voting on the CX rail with voting for MX voltages from the clock
driver. In addition, update the MMPLL7 FMAX table.

CRs-Fixed: 1063153
Change-Id: I296d2b151753be599a1db139e36f5e1eabe76791
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>