clk: iproc: Separate status and control variables

Some PLLs have separate registers for Status and Control.  The means the
pll_base needs to be split into 2 new variables, so that those PLLs can
specify device tree registers for those independently.  Also, add a new
driver flag to identify this presence of the split, and let the driver
know that additional registers need to be used.

Signed-off-by: Jon Mason <jonmason@broadcom.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>