hw/arm/Kconfig: Make StrongArm invisble in the menuconfig

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>
hw/Kconfig: Only source the devices

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>
hw/scsi/Kconfig: Create menu for 'SCSI devices'

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>
hw/*/Kconfig: Replace all 'select PCI' with 'depends on PCI'

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>