clk: Use clk_get_by_index_tail()

clk_get_by_index_tail() now handle common clk get by index
code so use it from clk_get_by_indexed_prop().

Cc: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>