namd: do not require single_node_gpu with rocm (#45650)

Removes conflict inadvertently left in #45553

var/spack/repos/builtin/packages/namd/package.py

@@ -104,7 +104,6 @@ class Namd(MakefilePackage, CudaPackage, ROCmPackage):
     depends_on("python", when="interface=python")
 
     conflicts("+avxtiles", when="@:2.14,3:", msg="AVXTiles algorithm requires NAMD 2.15")
-    conflicts("+rocm", when="~single_node_gpu")
     conflicts("+rocm", when="+cuda", msg="NAMD supports only one GPU backend at a time")
     conflicts("+single_node_gpu", when="~cuda~rocm")