aspeed: Add Aspeed global configuration file

Create a common Aspeed layer configuration file to host pointers to
things like u-boot and kernel trees that support SOCs from Aspeed.

Tested: Built image and verified in witherspoon qemu
Change-Id: I9ad2720d8b4dff191e43be0b2c1514d25d7bf3ef
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-openbmc-bsp/meta-aspeed/meta-ast2500/conf/machine/include/ast2500.inc b/meta-openbmc-bsp/meta-aspeed/meta-ast2500/conf/machine/include/ast2500.inc
index be75332..fe079ee 100644
--- a/meta-openbmc-bsp/meta-aspeed/meta-ast2500/conf/machine/include/ast2500.inc
+++ b/meta-openbmc-bsp/meta-aspeed/meta-ast2500/conf/machine/include/ast2500.inc
@@ -2,7 +2,7 @@
 #@NAME: Aspeed AST2500
 #@DESCRIPTION: Common machine configuration for the Aspeed AST2500 Chip
 
-PREFERRED_PROVIDER_virtual/kernel ?= "linux-obmc"
+require conf/machine/include/aspeed.inc
 
 UBOOT_MACHINE ?= "ast_g5_ncsi_config"
 UBOOT_ENTRYPOINT ?= "0x80001000"