efi_loader: don't use memmove() in efi_var_mem_del()

efi_var_mem_del() is in __efi_runtime because it would be needed for a
runtime implementation of SetVariable(). memmove() is not in __efi_runtime.
So we should not use it in efi_var_mem_del().

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

lib/efi_loader/efi_runtime.c

@@ -144,6 +144,8 @@ efi_status_t efi_init_runtime_supported(void)
  *
  * At runtime memcpy() is not available.
  *
+ * Overlapping memory areas can be copied safely if src >= dest.
+ *
  * @dest:	destination buffer
  * @src:	source buffer
  * @n:		number of bytes to copy