Rename and move kernel recipe

Rename linux-obmc to linux-aspeed and move to the Aspeed
layer.  Like recipes for u-boot forks, recipes for kernel
forks in support of different SOCs are typically provided
in the BSP supporting the SOC.

Moved a number of phosphor-isms out of the kernel recipe and put
those in a bbappend in aspeed-layer/bbappend.

Removed COMPATIBLE_MACHINE setting.  We simply use PREFERRED_PROVIDER
in machine configuration files to set the default kernel recipe.

Tested: Booted spoon/palmetto images using QEMU
Change-Id: I7dc73629cad4789dcd5aeb0f7b6214fe064c6adc
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openbmc-bsp/meta-aspeed/conf/machine/include/aspeed.inc b/meta-openbmc-bsp/meta-aspeed/conf/machine/include/aspeed.inc
index ff6c83e..88290ff 100644
--- a/meta-openbmc-bsp/meta-aspeed/conf/machine/include/aspeed.inc
+++ b/meta-openbmc-bsp/meta-aspeed/conf/machine/include/aspeed.inc
@@ -1,4 +1,4 @@
-PREFERRED_PROVIDER_virtual/kernel ?= "linux-obmc"
+PREFERRED_PROVIDER_virtual/kernel ?= "linux-aspeed"
 PREFERRED_PROVIDER_virtual/bootloader ?= "u-boot-aspeed"
 PREFERRED_PROVIDER_u-boot ?= "u-boot-aspeed"
 PREFERRED_PROVIDER_u-boot-fw-utils ?= "u-boot-fw-utils-aspeed"