clk: zynqmp: Check the return type

Currently the return value of of_clk_add_hw_provider is ignored.
lets check and return value.

Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/20210818065929.12835-2-shubhrajyoti.datta@xilinx.com


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