clk: zynqmp: Handle divider specific read only flag

Add support for divider specific read only CCF flag
(CLK_DIVIDER_READ_ONLY).

Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Link: https://lore.kernel.org/r/20210628070122.26217-5-rajan.vaja@xilinx.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>