[Hexagon] Add extenders for GD_PLT_B22_PCREL and LD_PLT_B22_PCREL

Patch by Sid Manning.

llvm-svn: 301955
diff --git a/llvm/lib/Target/Hexagon/HexagonMCInstLower.cpp b/llvm/lib/Target/Hexagon/HexagonMCInstLower.cpp
index 7189b5a..072501d 100644
--- a/llvm/lib/Target/Hexagon/HexagonMCInstLower.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonMCInstLower.cpp
@@ -39,7 +39,7 @@
   // Populate the relocation type based on Hexagon target flags
   // set on an operand
   MCSymbolRefExpr::VariantKind RelocationType;
-  switch (MO.getTargetFlags()) {
+  switch (MO.getTargetFlags() & ~HexagonII::HMOTF_ConstExtended) {
   default:
     RelocationType = MCSymbolRefExpr::VK_None;
     break;