nvmem: sunplus-ocotp: release otp->clk before return

Smatch reports:
drivers/nvmem/sunplus-ocotp.c:205 sp_ocotp_probe()
warn: 'otp->clk' from clk_prepare() not released on lines: 196.

In the function sp_ocotp_probe(struct platform_device *pdev), otp->clk may
not be released before return.

To fix this issue, using function clk_unprepare() to release otp->clk.

Fixes: 8747ec2e ("nvmem: Add driver for OCOTP in Sunplus SP7021")
Signed-off-by: Yi Yingao <m202271736@hust.edu.cn>
Reviewed-by: Dongliang Mu <dzm91@hust.edu.cn>
Message-ID: <20230509085237.5917-1-m202271736@hust.edu.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>