meta-aspeed: Set SOC_FAMILY in SoC include files

Set SOC_FAMILY to aspeed-g4 and aspeed-g5 in ast2400 and ast2500 SoC
include files, respectively.
Include soc-family.inc so that the family is added to MACHINEOVERRIDES.
This is just minor cleanup that helps set the scene for creating Aspeed
model-specific include files (though I don't plan to do this).

Tested: Inspected OVERRIDES with the bb utility. MACHINEOVERRIDES for
witherspoon is now "openbmc:armv6:aspeed-g5:witherspoon:ast2500".
Signed-off-by: Xo Wang <xow@google.com>
Change-Id: I4175915b750b04f36e7b3bd354a55b6a4f7f51fb
diff --git a/meta-ast2400/conf/machine/include/ast2400.inc b/meta-ast2400/conf/machine/include/ast2400.inc
index 0215a0d..49c6c23 100644
--- a/meta-ast2400/conf/machine/include/ast2400.inc
+++ b/meta-ast2400/conf/machine/include/ast2400.inc
@@ -14,6 +14,8 @@
 
 SERIAL_CONSOLES = "115200;ttyS4"
 
+SOC_FAMILY = "aspeed-g4"
+include conf/machine/include/soc-family.inc
 MACHINEOVERRIDES .= ":ast2400"
 
 require conf/machine/include/tune-arm926ejs.inc
diff --git a/meta-ast2500/conf/machine/include/ast2500.inc b/meta-ast2500/conf/machine/include/ast2500.inc
index 01f299c..2805ea0 100644
--- a/meta-ast2500/conf/machine/include/ast2500.inc
+++ b/meta-ast2500/conf/machine/include/ast2500.inc
@@ -14,6 +14,8 @@
 
 SERIAL_CONSOLES = "115200;ttyS4"
 
+SOC_FAMILY = "aspeed-g5"
+include conf/machine/include/soc-family.inc
 MACHINEOVERRIDES .= ":ast2500"
 
 require conf/machine/include/arm/arch-armv6.inc