Minor fix in constant regexp

Author: haneefdm

syntaxes/cortex-debug-disassembly.json

@@ -15,7 +15,7 @@
         {
             "comment": "Numeric constant",
             "name": "constant.numeric",
-            "match": "(0x[0-9A-F]+)|(#[0-9]+)"
+            "match": "(0x[0-9A-Fa-f]+)|(#[0-9]+)"
         },
         {
             "comment": "Register",
@@ -28,4 +28,4 @@
             "match": ";.*$"
         }
     ]
-}
+}