ports/WAVESHARE_RP2040_PLUS/board.json: Generalize for variants.

Remove the variant identifier from general board identifier keys.
Signed-off-by: RetiredWizard <github@RetiredWizard.com>

ports/rp2/boards/WAVESHARE_RP2040_PLUS/board.json

@@ -9,12 +9,12 @@
         "SPI Flash",
         "USB-C"
     ],
-    "id": "rp2-waveshare_rp2040_plus_4mb",
+    "id": "rp2-waveshare-rp2040-plus",
     "images": [
         "rp2040-plus-1_5.jpg"
     ],
     "mcu": "rp2040",
-    "product": "RP2040-Plus-4mb",
+    "product": "RP2040 Plus",
     "thumbnail": "",
     "url": "https://www.waveshare.com/rp2040-plus.htm",
     "variants": {