clk: mediatek: fix of_iomap memory leak

In the Linux kernel, the following vulnerability has been resolved:

clk: mediatek: fix of_iomap memory leak

Smatch reports:

drivers/clk/mediatek/clk-mtk.c:583 mtk_clk_simple_probe() warn:

'base' from of_iomap() not released on lines: 496.

This problem was also found in linux-next. In mtk_clk_simple_probe(),

base is not released when handling errors

if clk_data is not existed, which may cause a leak.

So free_base should be added here to release base.