camera: Fix loss of focus mode between shots

exynos_camera->focus_mode can't be relied upon to verify the previous
state, since a snapshot will reset the focus state. This was causing
any mode besides auto-focus (enum 0) to fail after the first photo
was taken, including the default continuous-picture.

Always make sure the focus-mode is up to date when set_params is
called

Change-Id: I8e6f52093ad897bcf04bc5047bb1fcd4f109dc55