panic: increase panic_timeout value to 5 second for bengal

During APSS shutdown, notification is send to modem
subsystem for completing cleanup callbacks and
preparing for minidump segments. Current delay of
200ms is not enough for modem to complete cleanup
and complete minidump preparation.

Increase panic_timeout to allow modem for completion
of cleanup and dump preparation.

Change-Id: Ic49b8910d4fc7288d4e760cd824cef8cca84ed00
Signed-off-by: Prateek Sood <prsood@codeaurora.org>