Commit 3cf5d076fb4d ("signal: Remove task parameter from force_sig") in
v5.3-rc1 drops second argument of force_sig(); before that, all callers
which passed something else than current task as second argument were
fixed, mostly to use send_sig() instead.

The situation in HostIF_SetFastClockRate() is the same as e.g. in bpfilter
call fixed by commit 1dfd1711de29 ("signal/bpfilter: Fix bpfilter_kernl to
use send_sig not force_sig"): locking in force_sig_info() cannot handle
task exiting and using force_sig() for SIGKILL is pointless anyway as this
signal cannot be blocked.

As send_sig() is present with unchanged signature since the pre-git era, we
can use send_sig() unconditionally, regardless of kernel version.