[Fix Pattern] Use root file system instead of loop device

[hukoyu]

Firstly, LKL memory is set to 32 MB in sgx-lkl. There is no sufficient memory to use loop device (RAMFS)
Secondly, some needed attributes not available in mounted root file system such as xattr, RENAME_EXCHANGE flag and so on.
That's why root file system workaround is used and /dev/vda mounted for root file system and used for some tests.

LTP tests fixed with this pattern: (Count: 45)

utime06
umount2_01, umount2_02, umount2_03
umount01, umount03
statx01, statx04
mount01
mknodat02
linkat02
chown04
fcntl24, fcntl25, fcntl26, fcntl32
fdatasync03
fgetxattr01, fgetxattr02, fgetxattr03
fsync01, fsync04
lchown03
rename11
renameat201, renameat202
listxattr01, listxattr02, listxattr03
lgetxattr01
lremovexattr01
llistxattr01, llistxattr02, llistxattr03
getxattr01, getxattr02, getxattr03
removexattr01
flistxattr01, flistxattr02, flistxattr03
fremovexattr01, fremovexattr02
fsetxattr01, fsetxattr02