loongarch/configs: Fix unknown filesystem type gfs2

kylin inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7KYTH


CVE: NA

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While mounting the filesystem named 'gfs2' with the command such as
"mount /dev/sda10 /mnt",
we get:
        "mount: /mnt: unknown filesystem type 'gfs2'"

Fix this by requiring "CONFIG_GFS2_FS=m" instead of
"# CONFIG_GFS2_FS is not set" in the loongson3_defconfig configuration file
After this commit, this issue is now resolved.
Tested on loongarch 3C5000.

Signed-off-by: mengfanhui <mengfanhui@kylinos.cn>