clk: meson: only one loop index is necessary in probe

We don't need several loop index variables in the probe function
This is far from being critical but since we are doing a vast
rework of meson clock controllers, now is the time to lower the
entropy a bit

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>