Btrfs: check_int: use the known block location

The xfstest btrfs/014 which tests the balance operation caused issues with
the check_int module. The attempt was made to use btrfs_map_block() to
find the physical location for a written block. However, this was not
at all needed since the location of the written block was known since
a hook to submit_bio() was the reason for entering the check_int module.
Additionally, after a block relocation it happened that btrfs_map_block()
failed causing misleading error messages afterwards.

This patch changes the check_int module to use the known information of
the physical location from the bio.

Reported-by: Wang Shilong <wangshilong1991@gmail.com>
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Tested-by: Wang Shilong <wangshilong1991@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>