quota: Allow Q_GETQUOTA for frozen filesystem

quota_cmd_write() forgot to list Q_GETQUOTA among commands allowed for
frozen filesystem. Thus Q_GETQUOTA quotactl would unnecessarily block
on frozen filesystems. Fix the issue by properly listing Q_GETQUOTA.

Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/quota.c

@@ -768,6 +768,7 @@ static int quotactl_cmd_write(int cmd)
 	switch (cmd) {
 	case Q_GETFMT:
 	case Q_GETINFO:
+	case Q_GETQUOTA:
 	case Q_GETNEXTQUOTA:
 	case Q_SYNC:
 	case Q_XGETQSTAT: