[AMDGPU] Added new encoding to getMCOpcodeGen

[rampitec]

Summary

Nothing breaks yet, but all encodings shall be in the map.

[kzhuravl]

LGTM

llvm/lib/Target/AMDGPU/SIInstrInfo.td

let ValueCols = [[!cast<string>(SIEncodingFamily.SI)],
                    [!cast<string>(SIEncodingFamily.SDWA9)],
                    // GFX80 encoding is added to work around a multiple matching
                    // issue for buffer instructions with unpacked d16 data. This
                    // does not actually change the encoding, and thus may be
                    // removed later.
                    [!cast<string>(SIEncodingFamily.GFX80)],
                    [!cast<string>(SIEncodingFamily.GFX9)],
                    [!cast<string>(SIEncodingFamily.GFX10)],
-                   [!cast<string>(SIEncodingFamily.SDWA10)]];
+                   [!cast<string>(SIEncodingFamily.SDWA10)],
+                   [!cast<string>(SIEncodingFamily.GFX10_B)]];
 }
 
 // Get equivalent SOPK instruction.
 def getSOPKOp : InstrMapping {
   let FilterClass = "SOPKInstTable";
   let RowFields = ["BaseCmpOp"];
   let ColFields = ["IsSOPK"];
   let KeyCol = ["0"];