CHROMIUM: Add #line to drivers/console/uart_console.c

Work around coreboot GCC preprocessor bug.

BUG=b:272518464
TEST=gcc -E drivers/console/uart_console.c

Change-Id: Ibe4dddb57f2a5060de741ea6b0ee0e6e9916a541
(cherry picked from commit 8672d4f4dc468615713230a254a7a723743b6cb6)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/4957626
Tested-by: Jeremy Bettis <jbettis@chromium.org>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>
Auto-Submit: Jeremy Bettis <jbettis@chromium.org>
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>

drivers/console/uart_console.c

@@ -13,6 +13,12 @@
  * Hooks into the printk and fputc (for printf) modules. Poll driven.
  */
 
+/*
+ * TODO(b/272518464): Work around coreboot GCC preprocessor bug.
+ * #line marks the *next* line, so it is off by one.
+ */
+#line 21
+
 #include <zephyr/kernel.h>
 
 #include <stdio.h>