lib/thread: Add ERROR prefix to error messages

This makes it easier to grep for errors.

BUG=b:179699789
TEST=Boot guybrush

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I7eecdfed6046b7d609069e7427f6883a4e9e521d
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58866
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>
diff --git a/src/lib/thread.c b/src/lib/thread.c
index da6189d..a075394 100644
--- a/src/lib/thread.c
+++ b/src/lib/thread.c
@@ -284,14 +284,14 @@
 
 	if (!thread_can_yield(current)) {
 		printk(BIOS_ERR,
-		       "thread_run() called from non-yielding context!\n");
+		       "ERROR: thread_run() called from non-yielding context!\n");
 		return -1;
 	}
 
 	t = get_free_thread();
 
 	if (t == NULL) {
-		printk(BIOS_ERR, "thread_run() No more threads!\n");
+		printk(BIOS_ERR, "ERROR: thread_run() No more threads!\n");
 		return -1;
 	}
 
@@ -319,14 +319,14 @@
 
 	if (!thread_can_yield(current)) {
 		printk(BIOS_ERR,
-		       "thread_run() called from non-yielding context!\n");
+		       "ERROR: thread_run() called from non-yielding context!\n");
 		return -1;
 	}
 
 	t = get_free_thread();
 
 	if (t == NULL) {
-		printk(BIOS_ERR, "thread_run() No more threads!\n");
+		printk(BIOS_ERR, "ERROR: thread_run() No more threads!\n");
 		return -1;
 	}