hw/intc/arm_gicv3: Set GICR_TYPER.Last correctly when nb_redist_regions > 1

hw/intc/arm_gicv3: Set GICR_TYPER.Last correctly when nb_redist_regions > 1

The 'Last' bit in the GICR_TYPER GICv3 redistributor register is
supposed to be set to 1 if this is the last redistributor in a series
of contiguous redistributor pages.  Currently we set Last only for
the redistributor for CPU (num_cpu - 1).  This only works if there is
a single redistributor region; if there are multiple redistributor
regions then we need to set the Last bit for the last redistributor
in each region.

This doesn't cause any problems currently because only the KVM GICv3
supports multiple redistributor regions, and it ignores the value in
GICv3State::gicr_typer.  But we need to fix this before we can enable
support for multiple regions in the emulated GICv3.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>