arm64: dts: fix #address-cells for foundation-v8

Commit 90556ca1

 ("arm64: vexpress: Add dts files for the ARMv8 RTSM
models") added foundation-v8.dts, but erroneously set
/cpus/#address-cells = <1> while providing two cells in each cpus/cpu@N
node's reg property.

As of commit ea393a2e ("arm64: smp: honour #address-size when parsing
CPU reg property") we read in as many address cells as specified rather
than always reading two. This means that for foundation-v8.dts, we only
read the first reg cell (zero) for each cpu node, and receive a lot of
warnings at boot of the form "/cpus/cpu@1: duplicate cpu reg properties
in the DT".

This patch corrects foundation-v8.dts to have the correct value for
/cpus/#address-cells.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Tested-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>