clocksource: hyper-v: make sure Invariant-TSC is used if it is available

clocksource: hyper-v: make sure Invariant-TSC is used if it is available

If Hyper-V TSC page is unavailable and Invariant-TSC is available,
currently hyperv_cs_msr (rather than Invariant-TSC) is used by default.

Use Invariant-TSC by default by downgrading hyperv_cs_msr.rating in
hv_init_tsc_clocksource(), if Invariant-TSC is available.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20230408210339.15085-1-decui@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>