check: Fix fs specfic imports when $FSTYPE!=$OLD_FSTYPE

check: Fix fs specfic imports when $FSTYPE!=$OLD_FSTYPE

Bug Description:

_test_mount function is failing with the following error:
./common/rc: line 4716: _xfs_prepare_for_eio_shutdown: command not found
check: failed to mount /dev/loop0 on /mnt1/test

when the second section in local.config file is xfs and the first section
is non-xfs.

It can be easily reproduced with the following local.config file

[s2]
export FSTYP=ext4
export TEST_DEV=/dev/loop0
export TEST_DIR=/mnt1/test
export SCRATCH_DEV=/dev/loop1
export SCRATCH_MNT=/mnt1/scratch

[s1]
export FSTYP=xfs
export TEST_DEV=/dev/loop0
export TEST_DIR=/mnt1/test
export SCRATCH_DEV=/dev/loop1
export SCRATCH_MNT=/mnt1/scratch

./check selftest/001

Root cause:
When _test_mount() is executed for the second section, the FSTYPE has
already changed but the new fs specific common/$FSTYP has not yet
been done. Hence _xfs_prepare_for_eio_shutdown() is not found and
the test run fails.

Fix:
Remove the additional _test_mount in check file just before ". common/rc"
since ". common/rc" is already sourcing fs specific imports and doing a
_test_mount.

Fixes: 1a49022fab9b4 ("fstests: always use fail-at-unmount semantics for XFS")
Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>