Add print macros, and use them for panic handling.

Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: I2314d417f485a6bd9aad2d6816fef42747eab194
diff --git a/pvmfw/src/main.rs b/pvmfw/src/main.rs
index 7156213..4ab14b7 100644
--- a/pvmfw/src/main.rs
+++ b/pvmfw/src/main.rs
@@ -21,7 +21,6 @@
 mod psci;
 mod uart;
 
-use console::emergency_write_str;
 use core::panic::PanicInfo;
 use psci::{system_off, system_reset};
 
@@ -29,7 +28,7 @@
 #[no_mangle]
 pub extern "C" fn main() -> ! {
     console::init();
-    console::write_str("Hello world\n");
+    println!("Hello world");
 
     system_off();
     #[allow(clippy::empty_loop)]
@@ -37,8 +36,8 @@
 }
 
 #[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    emergency_write_str("panic\n");
+fn panic(info: &PanicInfo) -> ! {
+    eprintln!("{}", info);
     system_reset();
     loop {}
 }