[llvm] [AMDGPU] Fix misspelled FileCheck prefixes and suffixes in tests (NFC) (PR #228001)

[Jay Foad via llvm-commits]

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@@ -8,7 +8,7 @@
 ; to follow a base one.
 
 ; GCN-LABEL: {{^}}out_of_order_merge:
-; GCN-COUNT2: ds_read2_b64
+; GCN-COUNT-2: ds_read2_b64
 ; GCN-COUNT3: ds_write_b64
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jayfoad wrote:

This also looks wrong!

https://github.com/llvm/llvm-project/pull/228001