defconfig: msm8937_32: Disable BUILD_ARM64_APPENDED_DTB_IMAGE flag

Add support to compile the kernel without the dtbs appended to it.
All the dtbs are concatenated to form dtb.img. Boot image with header
version 2 will now have this dtb.img added towards the end at an offset.

Change-Id: I0538d7744f1c7a8ef26885c1bb4277000e98146e
Signed-off-by: Rahul Shahare <rshaha@codeaurora.org>