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: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
Tested-by: Stefan Roese <sr@denx.de>