btrfs: return 0 for dev_extent_hole_check_zoned hole_start in case of error

Commit 7000babd ("btrfs: assign proper values to a bool variable in
dev_extent_hole_check_zoned") assigned false to the hole_start parameter
of dev_extent_hole_check_zoned().

The hole_start parameter is not boolean and returns the start location of
the found hole.

Fixes: 7000babd

 ("btrfs: assign proper values to a bool variable in dev_extent_hole_check_zoned")
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>