btrfs-progs: Remove deprecated leafsize usage

btrfs-progs: Remove deprecated leafsize usage

Leafsize is deprecated for a long time, and kernel has already updated
ctree.h to rename sb->leafsize to sb->__unused_leafsize.

This patch will remove normal users of leafsize:
1) Remove leafsize member from btrfs_root structure
   Now only root->nodesize and root->sectorisze.
   No longer root->leafsize.

2) Remove @leafsize parameter from btrfs_setup_root() function
   Since no root->leafsize, no need for @leafsize parameter.

The remaining user of leafsize will be:
1) btrfs inspect-internal dump-super
   Reformat the "leafsize" output to "leafsize (deprecated)" and
   use le32_to_cpu() to do the cast manually.

2) mkfs
   We still need to set sb->__unused_leafsize to nodesize.
   Do the manual cast too.

3) convert
   Same as mkfs, these two superblock setup should be merged later

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>