net: lwm2m: remove deprecated functions & definition

These functions have been deprecated for more than 2 releases,
remove them:

- lwm2m_engine_update_observer_min_period
- lwm2m_engine_update_observer_max_period
- lwm2m_engine_create_obj_inst
- lwm2m_engine_delete_obj_inst
- lwm2m_engine_set_opaque
- lwm2m_engine_set_string
- lwm2m_engine_set_u8
- lwm2m_engine_set_u16
- lwm2m_engine_set_u32
- lwm2m_engine_set_u64
- lwm2m_engine_set_s8
- lwm2m_engine_set_s16
- lwm2m_engine_set_s32
- lwm2m_engine_set_s64
- lwm2m_engine_set_bool
- lwm2m_engine_set_float
- lwm2m_engine_set_objlnk
- lwm2m_engine_set_time
- lwm2m_engine_get_opaque
- lwm2m_engine_get_string
- lwm2m_engine_get_u8
- lwm2m_engine_get_u16
- lwm2m_engine_get_u32
- lwm2m_engine_get_u64
- lwm2m_engine_get_s8
- lwm2m_engine_get_s16
- lwm2m_engine_get_s32
- lwm2m_engine_get_s64
- lwm2m_engine_get_bool
- lwm2m_engine_get_float
- lwm2m_engine_get_objlnk
- lwm2m_engine_get_time
- lwm2m_engine_register_read_callback
- lwm2m_engine_register_pre_write_callback
- lwm2m_engine_register_validate_callback
- lwm2m_engine_register_post_write_callback
- lwm2m_engine_register_exec_callback
- lwm2m_engine_register_create_callback
- lwm2m_engine_register_delete_callback
- lwm2m_engine_set_res_buf
- lwm2m_engine_set_res_data
- lwm2m_engine_set_res_data_len
- lwm2m_engine_get_res_buf
- lwm2m_engine_get_res_data
- lwm2m_engine_create_res_inst
- lwm2m_engine_delete_res_inst
- lwm2m_engine_path_is_observed
- lwm2m_engine_send
- lwm2m_send
- lwm2m_engine_enable_cache

And additionally, the following definition:
- LWM2M_RD_CLIENT_EVENT_REG_UPDATE_FAILURE

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
5 files changed