ueventd: fix extraneous 'Invalid section' error

When adding a new error case for host_init_parser, I didn't handle the
individual line callbacks used for ueventd correctly.  This change
fixes that.

Test: bullhead boots without extraneous ueventd warnings
Change-Id: I56cad854b0defd936a7fbcab73fe2f2963c0e2e4