hyperv: simplify and rename generate_guest_id

The generate_guest_id function is more suitable for use after the
following modifications.

1. The return value of the function is modified to u64.
2. Remove the d_info1 and d_info2 parameters from the function, keep the
   u64 type kernel_version parameter.
3. Rename the function to make it clearly a Hyper-V related function,
   and modify it to hv_generate_guest_id.

Signed-off-by: Li kunyu <kunyu@nfschina.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220928064046.3545-1-kunyu@nfschina.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>