fmap.h: Lint multiline comment

cpplint warns:

lib/fmap.h:75:  (cpplint) Complex multi-line /*...*/-style comment
found. Lint may give bogus warnings.  Consider replacing these with
//-style comments, with #if 0...#endif, or with more clearly structured
multi-line comments.  [readability/multiline_comment] [5]

It's easy enough to fit this on one line, so do it to avoid arguing with
the linter.

BUG=none
TEST=cros lint $(find -name '*.c' -o -name '*.h')

Change-Id: I86c5e88c01d5e38a531854e6063875202e4458fa
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashmap/+/5034760
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Commit-Queue: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
diff --git a/lib/fmap.h b/lib/fmap.h
index 05993fd..ca75a17 100644
--- a/lib/fmap.h
+++ b/lib/fmap.h
@@ -72,8 +72,7 @@
 	uint64_t base;			/* address of the firmware binary */
 	uint32_t size;			/* size of firmware binary in bytes */
 	uint8_t  name[FMAP_STRLEN];	/* name of this firmware binary */
-	uint16_t nareas;		/* number of areas described by
-					   fmap_areas[] below */
+	uint16_t nareas;		/* number of areas in fmap_areas[] */
 	struct fmap_area areas[];
 } __attribute__((packed));