When debugging is enabled and an unclean file-system is mounter,
the following assertion is triggered:

UBIFS assert failed in ubifs_tnc_start_commit at 805 (pid 1081)
Call Trace:
[cfaffbd0] [c0006cf8] show_stack+0x44/0x16c (unreliable)
[cfaffc10] [c011b738] ubifs_tnc_start_commit+0xbb8/0xd18
[cfaffc90] [c0112670] do_commit+0x150/0xa44
[cfaffd10] [c0125234] ubifs_rcvry_gc_commit+0xd8/0x544
[cfaffd60] [c0100e9c] ubifs_fill_super+0xe78/0x15f8
[cfaffdf0] [c0102118] ubifs_get_sb+0x20c/0x320
[cfaffe70] [c007f764] vfs_kern_mount+0x58/0xe0
[cfaffe90] [c007f83c] do_kern_mount+0x40/0xf8
[cfaffeb0] [c0095c24] do_mount+0x550/0x758
[cfafff10] [c0095ebc] sys_mount+0x90/0xe0
[cfafff40] [c000ed4c] ret_from_syscall+0x0/0x3c

The reason is that we initialize 'c->min_leb_idx' early, and do
not re-calculate it after journal replay.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>