build: Mark pci and pvh as x86_64 specific code

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

Author: retrage

src/main.rs

@@ -44,8 +44,10 @@ mod integration;
 mod loader;
 mod mem;
 mod part;
+#[cfg(target_arch = "x86_64")]
 mod pci;
 mod pe;
+#[cfg(target_arch = "x86_64")]
 mod pvh;
 #[cfg(target_arch = "x86_64")]
 mod rtc;