The workqueue used for monitoring the hardware may run while the device
is already suspended.  Fix this by using the freezable system workqueue
instead, cfr. commit 51e20d0e ("thermal: Prevent polling from
happening during system suspend").

Fixes: 608567aa ("thermal: da9062/61: Thermal junction temperature monitoring driver")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>