dt-bindings: mmc: sdhci-pxa: Fix 'regs' typo

The correct property name is 'reg' not 'regs'.

Fixes: ae5c0585 ("dt-bindings: mmc: Convert sdhci-pxa to json-schema")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231213224219.2191721-1-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mmc/sdhci-pxa.yaml

@@ -18,7 +18,7 @@ allOf:
             const: marvell,armada-380-sdhci
     then:
       properties:
-        regs:
+        reg:
           minItems: 3
         reg-names:
           minItems: 3
@@ -26,7 +26,7 @@ allOf:
         - reg-names
     else:
       properties:
-        regs:
+        reg:
           maxItems: 1
         reg-names:
           maxItems: 1