meson: rename target to update-hwdb-autosuspend

The script is renamed to match.

Now all targets are named uniformly in a tab-completion-friendly fashion, with
the exception of systemd-update-po which is generated by the i18n module
automatically:

$ ninja -C build -t targets | grep update
systemd-update-po: phony
update-syscall-tables: phony
update-syscall-header: phony
update-hwdb: phony
update-hwdb-autosuspend: phony
update-dbus-docs: CUSTOM_COMMAND
update-man-rules: CUSTOM_COMMAND