hpet: fix HPET_TN_SETVAL for high 32-bits of the comparator

hpet: fix HPET_TN_SETVAL for high 32-bits of the comparator

Commit 3787324101b ("hpet: Fix emulation of HPET_TN_SETVAL (Jan Kiszka)",
2009-04-17) applied the fix only to the low 32-bits of the comparator, but
it should be done for the high bits as well.  Otherwise, the high 32-bits
of the comparator cannot be written and they remain fixed to 0xffffffff.

Co-developed-by: TaiseiIto <taisei1212@outlook.jp>
Signed-off-by: TaiseiIto <taisei1212@outlook.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>