Remove the unifont dependency from build time with powerpc-ieee1275

This patch is applied in grub project. For more information:
commit: 0af7539bd297fb03da8166ba0c0c143cd2143fd2
author: Aaro Koskinen
====
--- a/configure.ac
+++ b/configure.ac
@@ -1633,11 +1633,11 @@
   FONT_SOURCE=
 fi
 
-if test "x$FONT_SOURCE" = x && ( test "x$platform" = xqemu || test "x$platform" = xloongson || test "x$platform" = xqemu_mips || test "x$target_cpu"-"$platform" = xpowerpc-ieee1275 || test "x$platform" = xcoreboot ); then
+if test "x$FONT_SOURCE" = x && ( test "x$platform" = xqemu || test "x$platform" = xloongson || test "x$platform" = xqemu_mips || test "x$platform" = xcoreboot ); then
   if test x"$grub_build_mkfont_excuse" = x ; then
-    AC_MSG_ERROR([qemu, powerpc-ieee1275, coreboot and loongson ports need unifont])
+    AC_MSG_ERROR([qemu, coreboot and loongson ports need unifont])
   else
-    AC_MSG_ERROR([qemu, powerpc-ieee1275, coreboot and loongson ports need unifont ($grub_build_mkfont_excuse)])
+    AC_MSG_ERROR([qemu, coreboot and loongson ports need unifont ($grub_build_mkfont_excuse)])
   fi
 fi