msm: clock-pll: Modify list_registers op for votable plls

Although votable PLLs may share the same interface, the underlying
PLL type may not be the same. Do not make assumptions about the PLL
register interface when printing out registers for debugging.

Change-Id: Ia033da62d6bc1aa0fd19aa3d51cf92b92ff35df6
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>