efi_loader: documentation of image loader

- Add missing function descriptions.
- Update existing function descriptions to match Sphinx style.
- Add lib/efi_loader/efi_image_loader.c to the input files for Sphinx
  generated documentation.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/Documentation/efi.rst b/Documentation/efi.rst
index 51c1de2..5337a55 100644
--- a/Documentation/efi.rst
+++ b/Documentation/efi.rst
@@ -9,6 +9,12 @@
 .. kernel-doc:: lib/efi_loader/efi_boottime.c
    :internal:
 
+Image relocation
+~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: lib/efi_loader/efi_image_loader.c
+   :internal:
+
 Runtime services
 ----------------