sm501: Add emulation of chip connected via PCI

Only the display controller part is created automatically on PCI

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Message-id: 647d292c6f5abba8b2a614687229949b5dcb864e.1492787889.git.balaton@eik.bme.hu
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>