efi_loader: correct comments for efi_status_t

EFI_STATUS is unsigned (UINTN). Hence it cannot be negative.
Correct comments for 'Return:'.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
index b9c2e4e..58f8fae 100644
--- a/lib/efi_loader/efi_variable.c
+++ b/lib/efi_loader/efi_variable.c
@@ -230,7 +230,7 @@
  * Those variables are *read-only* for users, efi_set_variable_common()
  * is called here.
  *
- * Return:	EFI_SUCCESS on success, status code (negative) on error
+ * Return:	status code
  */
 static efi_status_t efi_transfer_secure_state(enum efi_secure_mode mode)
 {
@@ -284,7 +284,7 @@
 /**
  * efi_init_secure_state - initialize secure boot state
  *
- * Return:	EFI_SUCCESS on success, status code (negative) on error
+ * Return:	status code
  */
 static efi_status_t efi_init_secure_state(void)
 {
@@ -438,7 +438,7 @@
  * attributes and signed time will also be returned in @env_attr and @time,
  * respectively.
  *
- * Return:	EFI_SUCCESS on success, status code (negative) on error
+ * Return:	status code
  */
 static efi_status_t efi_variable_authenticate(u16 *variable,
 					      const efi_guid_t *vendor,