arm64/numa: fix incorrect log for memory-less node

When booting on NUMA system with memory-less node (no
memory dimm on this memory controller), the print
for setup_node_data() is incorrect:

NUMA: Initmem setup node 2 [mem 0x00000000-0xffffffffffffffff]

It can be fixed by printing [mem 0x00000000-0x00000000] when
end_pfn is 0, but print <memory-less node> will be more useful.

Fixes: 1a2db300348b ("arm64, numa: Add NUMA support for arm64 platforms.")
Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ganapatrao Kulkarni <gkulkarni@caviumnetworks.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yisheng Xie <xieyisheng1@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>