mvebu arm64 for 4.6 (part 1)

Non dt part of the Armada 3700 support:
- Kconfig update
- defconfig update
- documentation update (including MAINTAINERS:)

* tag 'mvebu-arm64-4.6-1' of git://git.infradead.org/linux-mvebu:
  arm64: defconfig: enable Armada 3700 related config
  Documentation: arm: update supported Marvell EBU processors
  MAINTAINERS: Extend dts entry for ARM64 mvebu files
  arm64: add mvebu architecture entry
  irqchip/armada-370-xp: Do not enable it by default when ARCH_MVEBU is selected
  ARM: mvebu: Use the ARMADA_370_XP_IRQ option
  irqchip/armada-370-xp: Allow allocation of multiple MSIs
  irqchip/armada-370-xp: Use shorter names for irq_chip
  irqchip/armada-370-xp: Use PCI_MSI_DOORBELL_START where appropriate
  irqchip/armada-370-xp: Use the generic MSI infrastructure
  irqchip/armada-370-xp: Add Kconfig option for the driver
Signed-off-by: Olof Johansson <olof@lixom.net>