ANDROID: build.config.allmodconfig: Re-enable XFS_FS

It appears that the clang version we were using when we first introduced
build.config.allmodconfig had issues with XFS_FS, so 884416f5176a
("ANDROID: create build.configs for allmodconfig") made sure to disable
it.

Now that ACK uses an updated clang, attempt to re-enable that option.

Bug: 140224784
Bug: 140490203
Test: allmodconfig build for x86_64 and arm64
Fixes: 884416f5176a ("ANDROID: create build.configs for allmodconfig")
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: Iffdaaedb67162515af3b60ec62efd8f947ce17f2
[nc: Also drop comment, unlike the android-mainline version]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>