sony-laptop: merge Type4 into Type3

Creating Type4 was a mistake in the first place. Some users report that
also Type3 vaios require the same extra hotkey handling which the Type4
for was menat to guard from.
Merging down Type4 into Type3 will just remove a useless distinction.

Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>