Issue a deprecation warning if the user specifies the "-hdachs" option.

If the user needs to specify the disk geometry, the corresponding
parameters of the "-device ide-hd" option should be used instead.
"-hdachs" is considered as deprecated and might be removed soon.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>