mfd: Fix wrong wm8350-core kfree in error path

This patch includes below fixes:
1. fix wm8350_create_cache error path
   make sure wm8350->reg_cache is freed in error path.
2. fix wm8350_device_init error path
   no need to kfree(wm8350->reg_cache) in the case of goto out.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>