shader: decode unsigned byte loads into preserved low halves

Co-authored-by: fxpw <fxpw@outlook.com>

src/graphics/shader/recompiler/frontend/decode/ShaderDecoder.h

@@ -554,6 +554,7 @@ enum class Opcode {
 	BUFFER_STORE_FORMAT_XYZW,
 	BUFFER_STORE_FORMAT_D16_X,
 	BUFFER_LOAD_UBYTE,
+	BUFFER_LOAD_UBYTE_D16,
 	BUFFER_LOAD_SBYTE,
 	BUFFER_LOAD_USHORT,
 	BUFFER_LOAD_SSHORT,