tree 73df6cbc06f27122f88beb2eb309b77a51f7bce4
parent 5db9402a5f346e30288db228157f71c29aefce5a
author Kévin Redon <kredon@sysmocom.de> 1574105000 +0100
committer Kévin Redon <kredon@sysmocom.de> 1574105219 +0100

add DFU enter override capability

in case flashing the main application firmware using DFU failed,
the main application might be broken and not allow to switch again
to DFU mode to re-flash it correctly.
the other board have a way to force entering (e.g. staying in) the
bootloader using an external signal (e.g. a switch on the SIMtrace
board).
the OWHW DFU firmware did not have this functionality implemented.
the design (e.g. schematic) already has the SIMTRACE_BOOTLOADER
signal (on PA31) for this purpose.
now the DFU bootloader will start the DFU mode when the
SIMTRACE_BOOTLOADER is high.

this change has been tested on OWHWv2.

Change-Id: Iefff51a811ad0f3bf3a46b8e256b905d11344bea