media: venus: cleanup set_property controls

Move ptype (property type) initialization out of switch case
and save few lines of code.
Signed-off-by: NStanimir Varbanov <stanimir.varbanov@linaro.org>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>