linux: turn on vuart driver

Enable the vuart driver in the defconfig.

Based on the update to aspeed_defconfig in the linux repository.

Won't actually be enabled until the base recipe has the driver
merged again.

Signed-off-by: Milton Miller <miltonm@us.ibm.com>
diff --git a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
index 998323c..2b7d6e8 100644
--- a/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
+++ b/meta-ast2400/recipes-kernel/linux/linux-obmc/defconfig
@@ -122,6 +122,9 @@
 # CONFIG_SERIAL_8250_DMA is not set
 CONFIG_SERIAL_8250_NR_UARTS=6
 CONFIG_SERIAL_8250_RUNTIME_UARTS=6
+CONFIG_SERIAL_8250_EXTENDED=y
+CONFIG_SERIAL_8250_SHARE_IRQ=y
+CONFIG_SERIAL_ASPEED_VUART=y
 CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_HW_RANDOM=y
 CONFIG_I2C=y