ext4: When resizing set the EXT4_BG_INODE_ZEROED flag for new block groups

The inode table has been zeroed in setup_new_group_blocks().  Mark it as
such in ext4_group_add().  Since we are currently clearing inode table
for the new block group, we should set the EXT4_BG_INODE_ZEROED flag.
If at some point in the future we don't immediately zero out the inode
table as part of the resize operation, then obviously we shouldn't do
this.

Signed-off-by:  <Solofo.Ramangalahy@bull.net>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>