db845c/BoardConfig.mk: set bootv3 as the default

Re-enable vendor_boot by default for the db845c build

This was earlier enabled and then reverted. But should
be ok to re-enable now, as long as everyone is using
the flash-all.sh script that flashes vendor_boot.

Signed-off-by: Yongqin Liu <yongqin.liu@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: I819532a5a4d0e1ca41ac4947dd18f4932ecb2a78
1 file changed