btrfs-progs: use check_argc_* to check arg number for all tools

btrfs-progs: use check_argc_* to check arg number for all tools

Since this patch:
	btrfs-progs: move the check_argc_* functions into utils.c

All tools including the independent tools(e.g. btrfs-image, btrfs-convert)
can share the convenience of the check_argc_* functions, so this patch
adopt the argc check functions globally.

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>