mfd: Fix WM8994 error handling

This patch fixes wrong goto statement for error handling on probe.

Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>