arm64/hyperv: Add some missing functions to arm64

arm64/hyperv: Add some missing functions to arm64

These non-nested msr and fast hypercall functions are present in x86,
but they must be available in both architectures for the root partition
driver code.

While at it, remove the redundant 'extern' keywords from the
hv_do_hypercall() variants in asm-generic/mshyperv.h.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Roman Kisel <romank@linux.microsoft.com>
Link: https://lore.kernel.org/r/1741980536-3865-4-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1741980536-3865-4-git-send-email-nunodasneves@linux.microsoft.com>