Platform/RaspberryPi/Acpitables: Correct duplicate _UIDs

The new emmc2 device adds a container with a _UID of 0 which duplicates
an existing ACPI container.

This causes windows to fail to boot with a Stop ACPI_BIOS_ERROR.  The
workaround without this fix is to go into the BDS menus and set the SD
routing to the Arasan.

Fixes: 311ed3c7 ("Platform/RaspberryPi/Acpitables: Add eMMC2 device and tweak Arasan")
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>