erofs-utils: fix up "-E legacy-compress"

"-E legacy-compress" isn't parsed properly, fix it now.

Reported-by: Li Guifu <blucerlee@gmail.com>
Fixes: 1f11cf0463b5 ("erofs-utils: introduce extented options setting")
Reviewed-by: Li Guifu <blucerlee@gmail.com>
Signed-off-by: Gao Xiang <hsiangkao@aol.com>
1 file changed