ide/generic: Jmicron has its own drivers now

Drop ide-generic support for Jmicron identifiers as we now trust Jmicron.c for
this with drivers/ide.  The code check remains for the all-generic-ide case.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>