module: refactor load_module part 5

1) Extract out the relocation loop into apply_relocations
2) Extract license and version checks into check_module_license_and_versions
3) Extract icache flushing into flush_module_icache
4) Move __obsparm warning into find_module_sections
5) Move license setting into check_modinfo.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>