efi_loader: remove redundant statement

ascii2unicode() always ends the u16 string with '\0'.
Remove redundant assignment.

Add description for efi_str_to_u16() and ascii2unicode().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/include/efi_loader.h b/include/efi_loader.h
index 2855c01..5d522f1 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -411,7 +411,15 @@
 	(((_dp)->type == DEVICE_PATH_TYPE_##_type) && \
 	 ((_dp)->sub_type == DEVICE_PATH_SUB_TYPE_##_subtype))
 
-/* Convert strings from normal C strings to uEFI strings */
+/**
+ * ascii2unicode() - convert ASCII string to UTF-16 string
+ *
+ * A zero terminated ASCII string is converted to a zero terminated UTF-16
+ * string. The output buffer must be preassigned.
+ *
+ * @unicode:	preassigned output buffer for UTF-16 string
+ * @ascii:	ASCII string to be converted
+ */
 static inline void ascii2unicode(u16 *unicode, const char *ascii)
 {
 	while (*ascii)