ext4: migrate cleanup
ext4: migrate cleanup

This patch cleanup code a bit, actual logic not changed
- Move current block pointer to migrate_structure, let's all
  walk info will be in one structure.
- Get rid of usless null ind-block ptr checks, caller already
  does that check.

Signed-off-by: Dmitry Monakhov <eecfa5af1016ca9db755569d9919e212ab6a1c94@openvz.org>
Signed-off-by: "Theodore Ts'o" <4ed386e0495d3e109932df055831d9ec2f824927@mit.edu>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas