radio: iris: Allow user to set number of stations

Maximum number of stations to be searched passed from application
is not passed to FM Soc

Set max number of stations to be searched passed from framework
instead of always setting number of stations to zero

Change-Id: I7196d16bfdb86ea6fb1c6ec3d9ef7b7538001bec
CRs-Fixed: 421945
Signed-off-by: Ayaz Ahmad <aahmad@codeaurora.org>