cmd/internal/obj/ppc64: Fix RLDIMI

Fix the encoding of the SH field for rldimi.

The SH field of rldimi is 6-bit wide and it is not contiguous in the instruction.
Bits 0-4 are placed in bit fields 16-20 in the instruction, while bit 5 is
placed in bit field 30. The current implementation does not consider this and,
therefore, any SH field between 32 and 63 are encoded wrongly in the instruciton.

Change-Id: I4d25a0a70f4219569be0e18160dea5505bd7fff0
Reviewed-on: https://go-review.googlesource.com/37350
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>

src/cmd/internal/obj/ppc64/asm9.go

@@ -2721,6 +2721,9 @@ func asmout(ctxt *obj.Link, p *obj.Prog, o *Optab, out []uint32) {
 		case ARLDIMI, ARLDIMICC:
 			o1 = AOP_RRR(opirr(ctxt, p.As), uint32(p.Reg), uint32(p.To.Reg), (uint32(v) & 0x1F))
 			o1 |= (uint32(d) & 31) << 6
+			if d&0x20 != 0 {
+				o1 |= 1 << 5
+			}
 			if v&0x20 != 0 {
 				o1 |= 1 << 1
 			}