[PATCH] RX gas: fix DECNT register name

[Nick Clifton]

Hi Darius,

+2021-08-10  Darius Galis<darius.galis@cyberthorstudios.com>
+
+    * gas/config/rx-parse.y (DECNT): Fixed typo
+    * gas/testsuite/gas/rx/dpopm.sm (DECNT): Fixed typo
+    * gas/testsuite/gas/rx/dpushm.sm (DECNT): Fixed typo
+    * gas/testsuite/gas/rx/macros.inc (DECNT): Fixed typo

Patch approved and applied.

Cheers
   Nick