tlv_eeprom: Return -ENOSYS when system call is not available

When CMD_TLV_EEPROM is not enabled, use -ENOSYS, which is the correct
error code for U-Boot.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/tlv_eeprom.h b/include/tlv_eeprom.h
index 1de2fe2..a2c333e 100644
--- a/include/tlv_eeprom.h
+++ b/include/tlv_eeprom.h
@@ -114,19 +114,19 @@
 
 static inline int read_tlv_eeprom(void *eeprom, int offset, int len, int dev)
 {
-	return -ENOTSUPP;
+	return -ENOSYS;
 }
 
 static inline int write_tlv_eeprom(void *eeprom, int len)
 {
-	return -ENOTSUPP;
+	return -ENOSYS;
 }
 
 static inline int
 read_tlvinfo_tlv_eeprom(void *eeprom, struct tlvinfo_header **hdr,
 			struct tlvinfo_tlv **first_entry, int dev)
 {
-	return -ENOTSUPP;
+	return -ENOSYS;
 }
 
 #endif /* CONFIG_IS_ENABLED(CMD_TLV_EEPROM) */