powerpc/livepatch: Remove klp_write_module_reloc() stub

commit 425595a7 ("livepatch: reuse module loader code
to write relocations") offloads livepatch module relocation
write to arch specific module loader code.

Remove unused klp_write_module_reloc() function stub.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>