Linux 5.10 compat: also zvol_revalidate_disk()

Commit 59b6872 added a configure check for 5.10, which removed
revalidate_disk(), and conditionally replaced it's usage with a call to
the new revalidate_disk_size() function.  However, the old function also
invoked the device's registered callback, in our case
zvol_revalidate_disk().  This commit adds a call to zvol_revalidate_disk()
in zvol_update_volsize() to make sure the code path stays the same.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Michael D Labriola <michael.d.labriola@gmail.com>
Closes #11358

module/os/linux/zfs/zvol_os.c

@@ -644,11 +644,12 @@ zvol_revalidate_disk(struct gendisk *disk)
 static int
 zvol_update_volsize(zvol_state_t *zv, uint64_t volsize)
 {
+	struct gendisk *disk = zv->zv_zso->zvo_disk;
 
 #ifdef HAVE_REVALIDATE_DISK_SIZE
-	revalidate_disk_size(zv->zv_zso->zvo_disk, false);
+	revalidate_disk_size(disk, zvol_revalidate_disk(disk) == 0);
 #else
-	revalidate_disk(zv->zv_zso->zvo_disk);
+	revalidate_disk(disk);
 #endif
 	return (0);
 }