There is some rare cases where CPB (and possibly IDA) are missing on
processors.

This is the case fixed by commit f7f3dc00 ("x86/cpu/AMD: Fix
erratum 1076 (CPB bit)") and following.

In such context, the boost status isn't reported by
/sys/devices/system/cpu/cpufreq/boost.

This commit is about printing a message to report that the CPU
doesn't expose the boost capabilities.

This message could help debugging platforms hit by this phenomena.
Signed-off-by: Erwan Velu <e.velu@criteo.com>
[ rjw: Change the message text somewhat ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>