clk: meson: clk-pll: propagate the error from meson_clk_pll_set_rate()

Popagate the error code from meson_clk_pll_set_rate() when the PLL does
not lock with the new settings.

Fixes: 722825dc ("clk: meson: migrate plls clocks to clk_regmap")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20201226121556.975418-4-martin.blumenstingl@googlemail.com