Avoid unnecessary metaslab_check_free calling
The metaslab_check_free() function only needs to be called in the
GANG|DEDUP|etc case because zio_free_sync() will internally call
metaslab_check_free().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Signed-off-by: Finix1979 <yancw@info2soft.com>
Closes #13977