fm_fmri_hc_create() must call va_end() before returning

clang-tidy caught this.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes openzfs#14044

Author: ryao

module/zfs/fm.c

@@ -953,6 +953,7 @@ fm_fmri_hc_create(nvlist_t *fmri, int version, const nvlist_t *auth,
 			}
 			atomic_inc_64(
 			    &erpt_kstat_data.fmri_set_failed.value.ui64);
+			va_end(ap);
 			return;
 		}
 	}