Splitting out UEFI bootloader code from kernel

Now the bootloader should be responsible for all initial setup,
loading the kernel, and then handing off to the kernel with
proper data in place.

src/boot/utility.c

@@ -0,0 +1,18 @@
+#include <efi.h>
+
+struct ErrorCode {
+    EFI_STATUS code;
+    const CHAR16 *desc;
+};
+
+extern struct ErrorCode ErrorCodeTable[];
+
+const CHAR16 *util_error_message(EFI_STATUS status) {
+    int32_t i = -1;
+    while (ErrorCodeTable[++i].desc != NULL) {
+        if (ErrorCodeTable[i].code == status)
+            return ErrorCodeTable[i].desc;
+    }
+
+    return L"Unknown";
+}