meta-aspeed: MACHINEOVERRIDES fixups

OE-Core adds the value of SOC_FAMILY to MACHINEOVERRIDES, so explicitly
setting a MACHINEOVERRIDES is redundant.  Drop the explicit
ast2400/ast2500 MACHINEOVERRIDES and use the OE-Core provided aspeed-g4
and aspeed-g5 instead.

After the redundant ast2400/ast2500 overrides are dropped, the ordering
of the values in MACHINEOVERRIDES is wrong:
  MACHINEOVERRIDES="aspeed-g5:aspeed"

This means that:
  FOO_aspeed = "bar"

will override:
  FOO_aspeed-g5 = "baz"

which is the opposite of expectation.  The ordering is a function of
config file include order and choice of the predot vs postdot operator.
Use the same include ordering and dot operators as meta-fsl-arm to get
the overrides to appear in MACHINEOVERRIDES in the correct order such
that the expected semantics are provided and:
  FOO_aspeed-g5 = "bar"

will override:
  FOO_aspeed = "baz"

Drop explicit setting for FILESPATH as OE-Core adds OVERRIDES to
FILESPATH and bitbake will find the appropriate defconfig without them.
Move defconfigs to aspeed-g4 and aspeed-g5 since the ast2400 and ast2500
are being removed.

(From meta-aspeed rev: 85d614a69c1e752fb4d5917499500c37c4f745ac)

Change-Id: I63c0f71f14bf9145e7e769902be87bb267a78a30
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-aspeed/conf/machine/include/ast2400.inc b/meta-aspeed/conf/machine/include/ast2400.inc
index 2237475..a7c900a 100644
--- a/meta-aspeed/conf/machine/include/ast2400.inc
+++ b/meta-aspeed/conf/machine/include/ast2400.inc
@@ -2,7 +2,10 @@
 #@NAME: Aspeed AST2400
 #@DESCRIPTION: Common machine configuration for the Aspeed AST2400 Chip
 
+SOC_FAMILY = "aspeed-g4"
+include conf/machine/include/soc-family.inc
 require conf/machine/include/aspeed.inc
+require conf/machine/include/tune-arm926ejs.inc
 
 UBOOT_MACHINE ?= "ast_g4_ncsi_config"
 UBOOT_ENTRYPOINT ?= "0x40001000"
@@ -11,9 +14,3 @@
 MACHINE_EXTRA_RDEPENDS += "udev-aspeed-vuart"
 
 SERIAL_CONSOLES = "115200;ttyS4"
-
-SOC_FAMILY = "aspeed-g4"
-include conf/machine/include/soc-family.inc
-MACHINEOVERRIDES .= ":ast2400"
-
-require conf/machine/include/tune-arm926ejs.inc