Cleanup arch code, use asm instead of llvm_asm

src/arch/aarch64.rs

src/arch/aarch64/mod.rs

src/arch/x86_64.rs

src/arch/x86_64/mod.rs

src/main.rs

src/os/bios/panic.rs

src/os/uefi/arch/aarch64.rs

src/os/uefi/arch/aarch64/paging.rs

src/os/uefi/arch/x86_64.rs

src/os/uefi/arch/x86_64/paging.rs