defconfig: Enable minidump support for SDM845 target

Enable Minidump collection support for SDM845, which is used
to collect dumps from on field devices.

Change-Id: Ic749b534edd84589923e3d637cd0d8b53c0d740b
Signed-off-by: Lingutla Chandrasekhar <clingutla@codeaurora.org>