radio: iris: Fix the issue FM TX fails to turn on

FM TX fails to turn on as the condition to start
the turning process is incorrect.
Use proper condition to turn on FM TX.

CRs-Fixed: 529833
Change-Id: I01dc0620a10f1257f481f4089d392147fbf1ce8f
Signed-off-by: Ayaz Ahmad <aahmad@codeaurora.org>