defconfig: sdm845: Fix error of manual defconfig edit

Kernel tip <74c7425b>("ARM64: Add DT entry for msm-rtb") has errors
complaining about manual edits done to defconfig. Fix up the defconfig
files.

Change-Id: Ie3ec6313875a82d167e37641cde474bec079e91f
Signed-off-by: Kyle Yan <kyan@codeaurora.org>