kernel: Always build dtb targets before dtbo.img

Fixes:
error: unable to open output file
'arch/arm64/boot/dts/google/devices/bluejay/google-base/.gs101-b0.dtb.dts.tmp':
'No such file or directory'

Change-Id: I457062e46062fb3553421d196b432de7d06a49ad
1 file changed