zfs_setattr: fix atime update

In db4fc55 I messed up and changed this bit of code to set the inode
atime to an uninitialised value, when actually it was just supposed to
loading the atime from the inode to be stored in the SA. This changes it
to what it should have been.

Signed-off-by: Rob Norris <[email protected]>
Sponsered-by: https://despairlabs.com/sponsor/
Fixes: openzfs#15762

module/os/linux/zfs/zfs_vnops_os.c

@@ -2435,9 +2435,8 @@ zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zidmap_t *mnt_ns)
 
 	if ((mask & ATTR_ATIME) || zp->z_atime_dirty) {
 		zp->z_atime_dirty = B_FALSE;
-		inode_timespec_t tmp_atime;
+		inode_timespec_t tmp_atime = zpl_inode_get_atime(ip);
 		ZFS_TIME_ENCODE(&tmp_atime, atime);
-		zpl_inode_set_atime_to_ts(ZTOI(zp), tmp_atime);
 		SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zfsvfs), NULL,
 		    &atime, sizeof (atime));
 	}