dasd: fix error recovery for alias devices during format

Kernel panic or a hanging device during format if an alias device is
set offline or I/O errors occur.

Omit the error recovery procedure for alias devices and do retries on
the base device with full erp.

Signed-off-by: Stefan Haberland <stefan.haberland@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>