Change FDT memory type from runtime data to boot services data

Following Ard's suggestion:
Runtime data sections are intended for data that is used by the runtime
services implementation.
Let's change the type to EFI_BOOT_SERVICES_DATA.

This also fixes booting of armv7 using efi and fdtcontroladdr.

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>