extcon: max77693: Fix return value

Return the value obtained from the function instead of hardcoding.
Silences the following warnings:
drivers/extcon/extcon-max77693.c:297 max77693_muic_set_path()
info: why not propagate 'ret' from max77693_update_reg() instead of (-11)?
drivers/extcon/extcon-max77693.c:310 max77693_muic_set_path()
info: why not propagate 'ret' from max77693_update_reg() instead of (-11)?

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>