LoongArch: Default to a maximum page size of 64KiB

LoongArch: Default to a maximum page size of 64KiB

As per the spec (Section 7.5.10, LoongArch Reference Manual Vol. 1),
LoongArch machines are not limited in page size choices, and currently
page sizes of 4KiB, 16KiB and 64KiB are supported by mainline Linux.
While 16KiB is the most common, the current BFD code says it is the
maximum; this is not correct, and as an effect, almost all existing
binaries are incompatible with a 64KiB kernel because the sections are
not sufficiently aligned, while being totally fine otherwise.
This is needlessly complicating integration testing [1].

This patch fixes the inconsistency, and also brings BFD behavior in line
with that of LLD [2].

[1] https://github.com/loongson-community/discussions/issues/47
[2] https://github.com/llvm/llvm-project/blob/llvmorg-19.1.0/lld/ELF/Arch/LoongArch.cpp#L174-L183

bfd/
	* elfnn-loongarch.c (ELF_MAXPAGESIZE): Bump to 64KiB.
	(ELF_MINPAGESIZE): Define as 4KiB.
	(ELF_COMMONPAGESIZE): Define as 16KiB.

ld/
	* testsuite/ld-loongarch-elf/64_pcrel.d: Update assertions after
	changing the target max page size to 64KiB.
	* testsuite/ld-loongarch-elf/data-got.d: Likewise.
	* testsuite/ld-loongarch-elf/desc-relex.d: Likewise.
	* testsuite/ld-loongarch-elf/relax-align-ignore-start.d: Likewise.
	* testsuite/ld-loongarch-elf/tlsdesc_abs.d: Make the fuzzy match work
	as intended by not checking exact instruction words.
	* testsuite/ld-loongarch-elf/tlsdesc_extreme.d: Likewise.

Signed-off-by: WANG Xuerui <git@xen0n.name>