Use CONFIG_EXT4_FS instead of CONFIG_EXT3_FS in all of the defconfigs

Commit d6ace46c ("ext4: remove obsolete EXT3 config options")
removed the obsolete EXT3_CONFIG options, since it had been over a
decade since fs/ext3 had been removed.  Unfortunately, there were a
number of defconfigs that still used CONFIG_EXT3_FS which the cleanup
commit didn't fix up.  This led to a large number of defconfig test
builds to fail.  Oops.

Fixes: d6ace46c ("ext4: remove obsolete EXT3 config options")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>