cappuccino/ctrl: omit reset on spr_epcr

Value of spr_epcr is don't care until set explicitly anyways.
cappuccino/wb_mux: remove unused pc_i signal
cappuccino/wb_mux: omit reset for rf_result_o

Value is don't care until explicitly set.
cappuccino/wb_mux: remove !op_lsu_load_i restriction
cappuccino/decode_execute: omit reset on pc_execute_o
cappuccino/execute_ctrl: split ctrl_alu_result_o and ctrl_lsu_adr_o generation
cappuccino/fetch: omit reset of pc_decode

Value is don't care until explicitly set.
cappuccino/ctrl: change comment style to //
cappuccino/ctrl: remove enable signal on du_read_dat

The 'ack' signal will signal when data is valid,
so it's not needed to gate the data too.
execute_alu: move decoding of comp_op (op_setflag) to decode