Add BGA driver stub

drivers/bgad/Cargo.toml

@@ -0,0 +1,3 @@
+[package]
+name = "rtl8168d"
+version = "0.1.0"

drivers/bgad/src/main.rs

@@ -0,0 +1,13 @@
+use std::env;
+
+fn main() {
+    let mut args = env::args().skip(1);
+
+    let mut name = args.next().expect("bgad: no name provided");
+    name.push_str("_bga");
+
+    let bar_str = args.next().expect("bgad: no address provided");
+    let bar = usize::from_str_radix(&bar_str, 16).expect("bgad: failed to parse address");
+
+    print!("{}", format!(" + BGA {} on: {:X}\n", name, bar));
+}