kernel: Add mailbox and LPC drivers

Mailbox and LPC drivers:

 drivers/mailbox: Add Aspeed mailbox driver
 drivers/misc: Add Aspeed LPC control driver
 dt-bindings: Add Aspeed LPC Control bindings
 dt-bindings: Add Aspeed mailbox bindings

Enable the devices for Zaius and Witherspoon:

 ARM: dts: aspeed-bmc-opp-witherspoon: Enable mailbox and LPC control
 ARM: dts: aspeed-bmc-opp-zaius: Enable mailbox and LPC control node
 ARM: dts: aspeed-g5: Add mailbox and LPC control node

Change-Id: I8030404c5c2f6d90935bbd6b26de7143f564f06d
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
index f966919..771200c 100644
--- a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
+++ b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
@@ -75,6 +75,7 @@
 CONFIG_BLK_DEV_RAM=y
 CONFIG_BLK_DEV_RAM_COUNT=4
 CONFIG_BLK_DEV_RAM_SIZE=8192
+CONFIG_ASPEED_LPC_CTRL=y
 CONFIG_EEPROM_AT24=y
 CONFIG_NETDEVICES=y
 # CONFIG_NET_VENDOR_ARC is not set
@@ -143,6 +144,8 @@
 CONFIG_RTC_CLASS=y
 CONFIG_RTC_DRV_DS1307=y
 CONFIG_RTC_DRV_ASPEED=y
+CONFIG_MAILBOX=y
+CONFIG_ASPEED_MBOX=y
 # CONFIG_IOMMU_SUPPORT is not set
 CONFIG_FSI=y
 CONFIG_FSI_MASTER_GPIO=y