Delete unused found_init variable

Delete unused found_init variable

Spotted during compilation:

    passes/proc/proc_init.cc: In function ‘void {anonymous}::proc_init(Yosys::RTLIL::Module*, Yosys::SigMap&, Yosys::RTLIL::Process*)’:
    passes/proc/proc_init.cc:31:7: warning: variable ‘found_init’ set but not used [-Wunused-but-set-variable]