extcon: max77693: Fix modalias string

The platform device driver name is "max77693-muic", so advertise it
properly in the modalias string. This fixes automated module loading when
this driver is compiled as a module.

Fixes: db1b9037

 ("extcon: MAX77693: Add extcon-max77693 driver to support Maxim MAX77693 MUIC device")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>