kernel: Add ASPEED AST2500 DRM driver

This updates the kernel to include the ASPEED DRM driver.

Note that the defconfig update has no affect on the I2C support; it
drops out only due to being selected by other dependencies.

Joel Stanley (6):
      drm: Add ASPEED GFX driver
      drm: aspeed: Debugfs interface for GFX registers
      ARM: dts: aspeed-g5: Add resets and clocks to GFX node
      ARM: dts: ast2500-evb: Enable the GFX IP
      ARM: dts: witherspoon: Enable the GFX IP
      ARM: dts: aspeed-g5: Add DAC MUX userspace control

Change-Id: I084c4df8b7d4bcc183a865c9eabb0154570e0342
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/common/recipes-kernel/linux/linux-obmc_4.13.bb b/common/recipes-kernel/linux/linux-obmc_4.13.bb
index 58f2485..2d35c4a 100644
--- a/common/recipes-kernel/linux/linux-obmc_4.13.bb
+++ b/common/recipes-kernel/linux/linux-obmc_4.13.bb
@@ -1,6 +1,6 @@
 KBRANCH ?= "dev-4.13"
 LINUX_VERSION ?= "4.13.16"
 
-SRCREV="e8b7a01a0b0f611d48cdba2471ae6fbddeed17f5"
+SRCREV="5b5a9c2d51eda4279915d72cda387dd6edfd00df"
 
 require linux-obmc.inc