bmpblk: update comment for nissa

Remove the SD card description.

BUG=None
TEST=None
BRANCH=None

Change-Id: I988f264a5db9e486c716afdd1c82270dd032d8f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/bmpblk/+/3965878
Auto-Submit: Shou-Chieh Hsu <shouchieh@chromium.org>
Commit-Queue: Shou-Chieh Hsu <shouchieh@chromium.org>
Tested-by: Shou-Chieh Hsu <shouchieh@chromium.org>
Reviewed-by: Yu-Ping Wu <yupingso@chromium.org>
diff --git a/boards.yaml b/boards.yaml
index 5457c5d..418bfd6 100644
--- a/boards.yaml
+++ b/boards.yaml
@@ -342,7 +342,7 @@
   dpi: 96 # DO NOT COPY-PASTE. follow instructions above.
 
 nissa:
-  # 1920x1080, boots recovery image on any SD card or USB ports.
+  # 1920x1080, boots recovery image on any USB ports.
   screen: [1920, 1080]
   sdcard:   False
   dpi: 80  # DO NOT COPY-PASTE -- follow instructions at top of file.