prog_to_nir: OPCODE_EXP is not nir_op_fexp

It's a weird thing that provides some values related to 2**x.  It's also
already handled by a case in the switch.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Acked-by: Jason Ekstrand <jason.ekstrand@intel.com>

src/mesa/program/prog_to_nir.c

@@ -710,7 +710,7 @@ static const nir_op op_trans[MAX_OPCODE] = {
    [OPCODE_DST] = 0,
    [OPCODE_END] = 0,
    [OPCODE_EX2] = nir_op_fexp2,
-   [OPCODE_EXP] = nir_op_fexp,
+   [OPCODE_EXP] = 0,
    [OPCODE_FLR] = nir_op_ffloor,
    [OPCODE_FRC] = nir_op_ffract,
    [OPCODE_LG2] = nir_op_flog2,