FROMGIT: KVM: arm64: Make gen-hyprel endianness agnostic

gen-hyprel is, for better or worse, a native-endian program:
it assumes that the ELF data structures are in the host's
endianness, and even assumes that the compiled kernel is
little-endian in one particular case.

None of these assumptions hold true though: people actually build
(use?) BE arm64 kernels, and seem to avoid doing so on BE hosts.
Madness!

In order to solve this, wrap each access to the ELF data structures
with the required byte-swapping magic. This requires to obtain
the kernel data structure, and provide per-endianess wrappers.

This result in a kernel that links and even boots in a model.

Fixes: 8c49b5d4 ("KVM: arm64: Generate hyp relocation data")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit bc93763f
 git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git

 next)
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: Ib2b332ee2bf25c39d34fda6c9f50668491a1defd
Bug: 178098380
Test: atest VirtualizationHostTestCases on an EL2-enabled device