dt-bindings: vendor-prefixes: Add undocumented bm, gpio-key, and mentor prefixes

Add bm, gpio-key, and mentor as vendor prefixes which are in use, but
undocumented.
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/vendor-prefixes.yaml

@@ -16,7 +16,7 @@ properties: {}
 patternProperties:
   # Prefixes which are not vendors, but followed the pattern
   # DO NOT ADD NEW PROPERTIES TO THIS LIST
-  "^(at25|devbus|dmacap|dsa|exynos|fsi[ab]|gpio-fan|gpio|gpmc|hdmi|i2c-gpio),.*": true
+  "^(at25|bm|devbus|dmacap|dsa|exynos|fsi[ab]|gpio-fan|gpio-key|gpio|gpmc|hdmi|i2c-gpio),.*": true
   "^(keypad|m25p|max8952|max8997|max8998|mpmc),.*": true
   "^(pinctrl-single|#pinctrl-single|PowerPC),.*": true
   "^(pl022|pxa-mmc|rcar_sound|rotary-encoder|s5m8767|sdhci),.*": true
@@ -659,6 +659,8 @@ patternProperties:
     description: MEMSIC Inc.
   "^menlo,.*":
     description: Menlo Systems GmbH
+  "^mentor,.*":
+    description: Mentor Graphics
   "^meraki,.*":
     description: Cisco Meraki, LLC
   "^merrii,.*":