[AMDGPU] Silence gcc 7 warnings

Differential Revision: https://reviews.llvm.org/D59330

llvm-svn: 356100
diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index 9cc24ce..9361b25 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -925,7 +925,8 @@
 
     // Having a 0 op_sel_hi would require swizzling the output in the source
     // instruction, which we can't do.
-    unsigned UnsetMods = (Op == AMDGPU::V_PK_MAX_F16) ? SISrcMods::OP_SEL_1 : 0;
+    unsigned UnsetMods = (Op == AMDGPU::V_PK_MAX_F16) ? SISrcMods::OP_SEL_1
+                                                      : 0u;
     if (Src0Mods != UnsetMods && Src1Mods != UnsetMods)
       return nullptr;
     return Src0;