clk: zynqmp: move zynqmp_pll_set_mode out of round_rate callback

clk: zynqmp: move zynqmp_pll_set_mode out of round_rate callback

The round_rate callback should only perform rate calculation and not
involve calling zynqmp_pll_set_mode to change the pll mode. So let's
move zynqmp_pll_set_mode out of round_rate and to set_rate callback.

Fixes: 3fde0e16d016 ("drivers: clk: Add ZynqMP clock driver")
Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Quanyang Wang <quanyang.wang@windriver.com>
Link: https://lore.kernel.org/r/20210406154015.602779-1-quanyang.wang@windriver.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>