pinctrl: qcom: spmi-mpp: Fix err handling of pmic_mpp_set_mux

[ Upstream commit 69f8455f6cc78fa6cdf80d0105d7a748106271dc ]

'ret' should be returned while pmic_mpp_write_mode_ctl fails.

Fixes: 0e948042 ("pinctrl: qcom: spmi-mpp: Implement support for sink mode")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>