When page size larger than 16KB, arguments "vaddr + size(16KB)" in
"ioremap_page_range(vaddr, vaddr + size,...)" called by
"add_legacy_isa_io" is not page-aligned.

As loongson64 needs at least page size 16KB to get rid of cache alias,
and "vaddr" is 64KB-aligned, and 64KB is largest page size supported,
rounding "size" up to PAGE_SIZE is enough for all page size supported.

Fixes: 6d0068ad ("MIPS: Loongson64: Process ISA Node in DeviceTree")
Signed-off-by: Huang Pei <huangpei@loongson.cn>
Acked-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>