asm: Add att_syntax and raw options

As reported in issue cloud-hypervisor#143, recent nightly rustc fails to compile the
assembly file because it uses AT&T syntax. It is also suggested that use
raw option when using `include_str!` macro.

https://rust-lang.github.io/rfcs/2873-inline-asm.html#options-1
rust-lang/rust#86599

Signed-off-by: Akira Moroo <[email protected]>

Author: retrage

src/asm/mod.rs

@@ -1 +1 @@
-global_asm!(include_str!("ram32.s"));
+global_asm!(include_str!("ram32.s"), options(att_syntax, raw));