cmd/internal/obj/ppc64: Fix RLDIMI
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 <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Lynn Boger <b27445fe6fb259c37b8e0a4ce56e22e2413754bf@linux.vnet.ibm.com>

derekmarcotte/go,akutz/go,vsekhar/elastic-go,Cofyc/go,vsekhar/elastic-go,akutz/go,nawawi/go,Cofyc/go,akutz/go,linux-on-ibm-z/go,codestation/go,nawawi/go,josharian/go,golang/go,polyverse-security/go,derekmarcotte/go,codestation/go,Cofyc/go,ImJasonH/go,CAFxX/go,golang/go,CAFxX/go,josharian/go,akutz/go,derekmarcotte/go,codestation/go,golang/go,codestation/go,ImJasonH/go,nawawi/go,cloudflare/go,christopher-henderson/Go,nawawi/go,golang/go,cloudflare/go,vsekhar/elastic-go,derekmarcotte/go,josharian/go,josharian/go,linux-on-ibm-z/go,CAFxX/go,josharian/go,Cofyc/go,akutz/go,linux-on-ibm-z/go,akutz/go,polyverse-security/go,CAFxX/go,ImJasonH/go,akutz/go,Cofyc/go,linux-on-ibm-z/go,codestation/go,CAFxX/go,nawawi/go,ImJasonH/go,polyverse-security/go,polyverse-security/go,josharian/go,josharian/go,CAFxX/go,Cofyc/go,cloudflare/go,ImJasonH/go,ImJasonH/go,derekmarcotte/go,codestation/go,polyverse-security/go,vsekhar/elastic-go,nawawi/go,Cofyc/go,linux-on-ibm-z/go,ImJasonH/go,Cofyc/go,golang/go,vsekhar/elastic-go,ImJasonH/go,cloudflare/go,codestation/go,cloudflare/go,polyverse-security/go,golang/go,cloudflare/go,cloudflare/go,nawawi/go,josharian/go,codestation/go,vsekhar/elastic-go,linux-on-ibm-z/go,golang/go,derekmarcotte/go,golang/go,nawawi/go,akutz/go,polyverse-security/go,CAFxX/go,linux-on-ibm-z/go,derekmarcotte/go,derekmarcotte/go,cloudflare/go,linux-on-ibm-z/go,vsekhar/elastic-go,vsekhar/elastic-go,CAFxX/go,polyverse-security/go