unnessacary `Vec::retain` when executing sc.d/w instruction

[lenawanel]

https://github.com/d0iasm/rvemu/blob/f55eb5b376f22a73c0cf2630848c03f8d5c93922/src/cpu.rs#L1814 https://github.com/d0iasm/rvemu/blob/f55eb5b376f22a73c0cf2630848c03f8d5c93922/src/cpu.rs#L1793

both of these lines do nothing, as https://github.com/d0iasm/rvemu/blob/f55eb5b376f22a73c0cf2630848c03f8d5c93922/src/cpu.rs#L1786 already has shown that addr is not in the reservation set, when reaching these lines.