thermal: intel: hfi: Improve the type of hfi_features::nr_table_pages

A Coverity static code scan raised a potential overflow_before_widen
warning when hfi_features::nr_table_pages is used as an argument to
memcpy in intel_hfi_process_event().

Even though the overflow can never happen (the maximum number of pages of
the HFI table is 0x10 and 0x10 << PAGE_SHIFT = 0x10000), using size_t as
the data type of hfi_features::nr_table_pages makes Coverity happy and
matches the data type of the argument 'size' of memcpy().

Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>