OvmfPkg: fix PcdFSBClock

kvm FSB clock is 1GHz, not 100 MHz.  Timings are off by factor 10.
Fix all affected build configurations.  Not changed: Microvm and
Cloudhw (they have already have the correct value), and Xen (has
no fixed frequency, the PCD is configured at runtime by platform
initialization code).

Fixes: c37cbc030d96 ("OvmfPkg: Switch timer in build time for OvmfPkg")
Reported-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>