Extend smbios api to allow runtime change of mainboard serial and version

This patch extends the current smbios api to allow changing mainboard
serial and version during coreboot runtime. This is helpful if you
have an EEPROM etc. to access these informations and want to add
some quirks for broken hardware revision for the linux kernel.
This could be done via DMI_MATCH marco.

Change-Id: I1924a56073084e965a23e47873d9f8542070423c
Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-on: http://review.coreboot.org/1232
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
diff --git a/src/include/smbios.h b/src/include/smbios.h
index c6585155..50bce2a 100644
--- a/src/include/smbios.h
+++ b/src/include/smbios.h
@@ -7,6 +7,9 @@
 int smbios_add_string(char *start, const char *str);
 int smbios_string_table_len(char *start);
 
+const char *smbios_mainboard_serial_number(void);
+const char *smbios_mainboard_version(void);
+
 #define BIOS_CHARACTERISTICS_PCI_SUPPORTED  (1 << 7)
 #define BIOS_CHARACTERISTICS_PC_CARD  (1 << 8)
 #define BIOS_CHARACTERISTICS_PNP  (1 << 9)