doc: efi: Add the EFI-loader API documentation

Bring in the documentation from the efi_loader.h header file, so we can
see the API defined there.

Fix efi_alloc() to avoid a warning.

Signed-off-by: Simon Glass <sjg@chromium.org>
Suggested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>

doc/api/efi.rst

@@ -54,6 +54,12 @@ drivers, handles, loaded images, and the memory map).
 .. kernel-doc:: cmd/efidebug.c
    :internal:
 
+Overall API
+-----------
+
+.. kernel-doc:: include/efi_loader.h
+   :internal:
+
 Initialization of the UEFI sub-system
 -------------------------------------
 

include/efi_loader.h

@@ -764,7 +764,7 @@ efi_status_t efi_next_variable_name(efi_uintn_t *size, u16 **buf,
  *
  * Allocate memory from pool and zero it out.
  *
- * @size:	number of bytes to allocate
+ * @len:	number of bytes to allocate
  * Return:	pointer to allocated memory or NULL
  */
 void *efi_alloc(size_t len);