implement io based udelay function for all mainboards that lack an apic

timer (or just failed otherwise due to missing udelay)


git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2131 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

src/config/Options.lb

@@ -784,6 +784,11 @@ define CONFIG_UDELAY_TSC
 	export used
 	comment "Implement udelay with the x86 time stamp counter"
 end
+define CONFIG_UDELAY_IO
+	default 0
+	export used
+	comment "Implement udelay with x86 io registers"
+end
 define FAKE_SPDROM
 	default 0
 	export always