Changes

smdpp_Tests: rename f_rsp_client_init to f_init_es9plus

We already have an init function for ES2+ that is called f_init_es2plus,
let's rename f_rsp_client_init to maintain consistency.

Related: SYS#7339
Change-Id: I865b9dfc3597f9a962225880b7a5cda838b8377e