Yocto 2.3

Move OpenBMC to Yocto 2.3(pyro).

Tested: Built and verified Witherspoon and Palmetto images
Change-Id: I50744030e771f4850afc2a93a10d3507e76d36bc
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Resolves: openbmc/openbmc#2461
diff --git a/import-layers/meta-raspberrypi/conf/machine/raspberrypi0.conf b/import-layers/meta-raspberrypi/conf/machine/raspberrypi0.conf
index 7c2b811..3bd9e95 100644
--- a/import-layers/meta-raspberrypi/conf/machine/raspberrypi0.conf
+++ b/import-layers/meta-raspberrypi/conf/machine/raspberrypi0.conf
@@ -5,5 +5,5 @@
 MACHINEOVERRIDES = "raspberrypi:${MACHINE}"
 include conf/machine/raspberrypi.conf
 
-SERIAL_CONSOLE = "115200 ttyAMA0"
+SERIAL_CONSOLE ?= "115200 ttyAMA0"
 VC4_CMA_SIZE ?= "cma-128"