oprofile, s390: Remove hwsampler_files.c and merge it into init.c

Merge the contents of hwsampler_files.c into
arch/s390/oprofile/init.c.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>