s390/cpum_sf: Add data entry sizes to sampling trailer entry

The CPU Measurement sampling facility creates a trailer entry for each
Sample-Data-Block of stored samples. The trailer entry contains the sizes
(in bytes) of the stored sampling types:
 - basic-sampling data entry size
 - diagnostic-sampling data entry size
Both sizes are 2 bytes long.

This patch changes the trailer entry definition to reflect this.

Fixes: fcc77f50 ("s390/cpum_sf: Atomically reset trailer entry fields of sample-data-blocks")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>