btrfs-progs: remove wrong set_argv0 for restore

btrfs-progs: remove wrong set_argv0 for restore

Before this patch, you could see the following after exec restore
	# :too few arguments

The tool name "btrfs restore" is missing.

The @set_argv0() function is introduced by:
	commit a184abc70f7b1468e6036ab576f1587ee0574668
	btrfs-progs: move the check_argc_* functions into utils.c
	...
	Also add a new function "set_argv0" to set the correct tool name:
        *btrfs-image*: too few arguments

But @set_argv0() only applies to the independent tools with
the name pattern btrfs-***.
Since restore is now is subcommand under "btrfs",
there is no need to use @set_argv0() before check_argc_* to
repair the prompt tool name before "too few arguments".

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