arm64: Use correct method to calculate nomap region boundaries

Nomap regions are treated as "reserved". When region boundaries are not
page aligned, we usually increase the "reserved" regions rather than
decrease them. So, we should use memblock_region_reserved_base_pfn()/
memblock_region_reserved_end_pfn() instead of memblock_region_memory_
base_pfn()/memblock_region_memory_base_pfn() to calculate boundaries.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/r/20211022070646.41923-1-chenhuacai@loongson.cn


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>