[AMDGPU] gfx1250 does not need nop before VGPR dealloc (#153844)

This has no impact as the dealloc is now practically disabled.

Author: rampitec

llvm/lib/Target/AMDGPU/GCNSubtarget.h

@@ -1799,11 +1799,7 @@ class GCNSubtarget final : public AMDGPUGenSubtargetInfo,
 
   // \returns true if the subtarget has a hazard requiring an "s_nop 0"
   // instruction before "s_sendmsg sendmsg(MSG_DEALLOC_VGPRS)".
-  bool requiresNopBeforeDeallocVGPRs() const {
-    // Currently all targets that support the dealloc VGPRs message also require
-    // the nop.
-    return true;
-  }
+  bool requiresNopBeforeDeallocVGPRs() const { return !GFX1250Insts; }
 
   bool isDynamicVGPREnabled() const { return DynamicVGPR; }
   unsigned getDynamicVGPRBlockSize() const {