Enable download mode on framework watchdog, based on property

Enabling download mode allows to get better insight of the
device state at the time of framework watchdog.

Also moving the SysRq triggers inside the conditional block
to avoid watchdog bark and to ensure traces are collected
before dumping blocked threads and CPU backtraces.

Change-Id: I444e550af0e23053f34b3d47db07c67c6f43133f