mfd: stmfx: Fix error path in stmfx_chip_init

In error path, disable vdd regulator if it exists, but don't overload ret.
Because if regulator_disable() is successful, stmfx_chip_init will exit
successfully while chip init failed.

Fixes: 06252ad ("mfd: Add ST Multi-Function eXpander (STMFX) core driver")
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20230609092804.793100-1-amelie.delaunay@foss.st.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: ADESTM

drivers/mfd/stmfx.c

@@ -387,7 +387,7 @@ static int stmfx_chip_init(struct i2c_client *client)
 
 err:
 	if (stmfx->vdd)
-		return regulator_disable(stmfx->vdd);
+		regulator_disable(stmfx->vdd);
 
 	return ret;
 }