btrfs-progs: fix max mirror number error for chunk-recover
When run chunk-recover on a health btrfs(data profile raid0, with
plenty of data), the program has a chance to abort on the number
of mirrors of an extent.
According to the kernel code, the max mirror number of an extent
is 3 not 2:
ctree.h: BTRFS_MAX_MIRRORS 3
chunk-recover.c : BTRFS_NUM_MIRRORS 2
just change BTRFS_NUM_MIRRORS to 3, and everything goes well.
Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>