defconfig: msm: Disable EXT2 and EXT3 FS configs for MSM8998

This is required to fix the VTS test case failures which are failing
as the kernel supports EXT2/EXT3 but the tools mkfs.ext2/mkfs.ext3
doesn't exist anymore.

Change-Id: Iaa17b827439e4f775cdfe9044d35b8a0155f8f08
Signed-off-by: Naitik Bharadiya <bharad@codeaurora.org>