Fixup VGA init fail bug,flush the L2 D-Cache before reading pci rom space

Change-Id: I0a3e872612252db2dab70968c738d7516eb5091d
Target:2G5536

x86emu/src/biosemu/freebiosvga.c

@@ -71,7 +71,9 @@ int vga_bios_init(void)
        		}
 #endif
 		printf("Rom mapped to %lx\n",romaddress);
-
+#ifdef LOONGSON_2G5536
+		pci_sync_cache(magic,romaddress,2, SYNC_W);
+#endif
 		magic[0] = readb(romaddress);
 		magic[1] = readb(romaddress + 1);
 
@@ -83,6 +85,9 @@ int vga_bios_init(void)
 			printf("rom size is %ldk\n",romsize/1024);
 
 			ppcidata = readw(romaddress + 0x18);
+#ifdef LOONGSON_2G5536
+			pci_sync_cache(pcisig,romaddress + ppcidata,4, SYNC_W);
+#endif
 			printf("PCI data structure at offset %x\n",ppcidata);
 			pcisig[0] = readb(romaddress + ppcidata);
 			pcisig[1] = readb(romaddress + ppcidata + 1);