src: change coreboot to lowercase

The word 'coreboot' should always be written in lowercase, even at the
start of a sentence.

Change-Id: I7945ddb988262e7483da4e623cedf972380e65a2
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/20029
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/include/memrange.h

@@ -21,7 +21,7 @@
  * is exposed so that a memranges can be used on the stack if needed. */
 struct memranges {
 	struct range_entry *entries;
-	/* Coreboot doesn't have a free() function. Therefore, keep a cache of
+	/* coreboot doesn't have a free() function. Therefore, keep a cache of
 	 * free'd entries.  */
 	struct range_entry *free_list;
 };