mb/prodrive/hermes: Implement smbios_mainboard_version

Return the HSI version read from BMC in smbios_mainboard_version.

Change-Id: If907d598c9e05d35f8898d294678f61d075f935a
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55712
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/mainboard/prodrive/hermes/smbios.c

@@ -2,6 +2,7 @@
 
 #include <smbios.h>
 #include <types.h>
+#include <string.h>
 
 #include "variants/baseboard/include/eeprom.h"
 
@@ -26,3 +27,12 @@ const char *smbios_mainboard_serial_number(void)
 	else
 		return CONFIG_MAINBOARD_SERIAL_NUMBER;
 }
+
+const char *smbios_mainboard_version(void)
+{
+	static char version_str[8] = { 0 };
+
+	snprintf(version_str, sizeof(version_str), "HSI %u", get_bmc_hsi());
+
+	return version_str;
+}