IDE: bail out of dev_print() for unknown device types

Commit 574b3195 introduced a subtle bug by mixing a list of tests
for "dev_desc->type" and "dev_desc->if_type" into one switch(), which
then mostly did not work because "dev_desc->type" cannot take any
"IF_*" type values. A later fix in commit 8ec6e332 changed the
switch() into testing "dev_desc->if_type", but at this point the
initial test for unknown device types was completely lost, which
resulted in output like that for IDE ports without device attached:

  Device 1: Model:  Firm:  Ser#:
            Type: # 1F #
            Capacity: not available

This patch re-introduces the missing test for unknown device types.
Signed-off-by: NWolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
Tested-by: NStefan Roese <sr@denx.de>

disk/part.c

@@ -114,6 +114,11 @@ void dev_print (block_dev_desc_t *dev_desc)
 	lbaint_t lba512;
 #endif
 
+	if (dev_desc->type == DEV_TYPE_UNKNOWN) {
+		puts ("not available\n");
+		return;
+	}
+
 	switch (dev_desc->if_type) {
 	case IF_TYPE_SCSI:
 		printf ("(%d:%d) Vendor: %s Prod.: %s Rev: %s\n",