Remove XTIMEOUT from TestRegisters on linux

I suspect the test was hanging due to the attach deadlock. This was fixed and the test has passed
last 200 buildbot runs.

llvm-svn: 256755
diff --git a/lldb/packages/Python/lldbsuite/test/dosep.py b/lldb/packages/Python/lldbsuite/test/dosep.py
index e1f0660..8733fc6 100644
--- a/lldb/packages/Python/lldbsuite/test/dosep.py
+++ b/lldb/packages/Python/lldbsuite/test/dosep.py
@@ -1148,7 +1148,6 @@
         expected_timeout |= {
             "TestEvents.py",
             "TestMultithreaded.py",
-            "TestRegisters.py",  # ~12/600 dosep runs (build 3120-3122)
         }
     elif target.startswith("android"):
         expected_timeout |= {