clk: mvebu: armada-37xx-tbg: Remove the unneeded result variable

Return the value of_clk_add_hw_provider() directly instead of storing it
in another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/20220906072322.337253-1-ye.xingchen@zte.com.cn


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