ppc/ppc405: QOM'ify MAL

ppc/ppc405: QOM'ify MAL

The Memory Access Layer (MAL) controller is currently modeled as a DCR
device with 4 IRQs. Also drop the ppc4xx_mal_init() helper and adapt
the sam460ex machine.

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
[balaton: ppc4xx_dcr_register changes, add finalize method]
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-Id: <d54a243dff94d95ba30dbcc09c27700a90ade932.1660746880.git.balaton@eik.bme.hu>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>