Remove some unused imports

Former-commit-id: 64bd0e7419cd374f6321fcc3bd9fdee7a241592b

src/core/arm7tdmi/exception.rs

@@ -1,6 +1,5 @@
 use super::super::sysbus::SysBus;
 use super::cpu::{Core, PipelineState};
-use super::REG_LR;
 use super::{CpuMode, CpuState};
 use colored::*;
 

src/core/arm7tdmi/thumb/exec.rs

@@ -1,4 +1,3 @@
-use crate::core::arm7tdmi::alu::AluOpCode;
 use crate::core::arm7tdmi::bus::Bus;
 use crate::core::arm7tdmi::cpu::{Core, CpuExecResult};
 use crate::core::arm7tdmi::*;