thunderbolt: Make tb_eeprom_get_drom_offset static

tb_eeprom_get_drom_offset is local to this file.
Signed-off-by: NAndreas Noever <andreas.noever@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/thunderbolt/eeprom.c

@@ -233,7 +233,7 @@ struct tb_drom_entry_port {
 /**
  * tb_eeprom_get_drom_offset - get drom offset within eeprom
  */
-int tb_eeprom_get_drom_offset(struct tb_switch *sw, u16 *offset)
+static int tb_eeprom_get_drom_offset(struct tb_switch *sw, u16 *offset)
 {
 	struct tb_cap_plug_events cap;
 	int res;