defconfig: enable writeback for 7x30

Update defconfig with writeback configuration enabled for 7x30

CRs-Fixed: 313524
Change-Id: Id99214bf1468f425bb5bae8cd00f9fcb03b9b41d
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>
Signed-off-by: Mayank Chopra <makchopra@codeaurora.org>
2 files changed