cmd/compile: remove unused cases from switch
cmd/compile: remove unused cases from switch

The first just falls through, and the default case does nothing. They
can be deleted.

Change-Id: I82ab1ce3acde0b8423334cfbf35f9e0c806cd494
Reviewed-on: https://go-review.googlesource.com/65410
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

codestation/go,josharian/go,nawawi/go,akutz/go,CAFxX/go,codestation/go,nawawi/go,akutz/go,akutz/go,josharian/go,nawawi/go,codestation/go,cloudflare/go,CAFxX/go,akutz/go,josharian/go,polyverse-security/go,akutz/go,josharian/go,cloudflare/go,Cofyc/go,akutz/go,josharian/go,CAFxX/go,CAFxX/go,Cofyc/go,Cofyc/go,nawawi/go,golang/go,polyverse-security/go,cloudflare/go,polyverse-security/go,codestation/go,golang/go,cloudflare/go,golang/go,akutz/go,golang/go,CAFxX/go,golang/go,cloudflare/go,nawawi/go,josharian/go,codestation/go,nawawi/go,cloudflare/go,golang/go,polyverse-security/go,golang/go,polyverse-security/go,cloudflare/go,CAFxX/go,codestation/go,nawawi/go,Cofyc/go,Cofyc/go,akutz/go,Cofyc/go,CAFxX/go,josharian/go,Cofyc/go,golang/go,polyverse-security/go,codestation/go,josharian/go,nawawi/go,cloudflare/go,polyverse-security/go,christopher-henderson/Go,codestation/go,Cofyc/go,CAFxX/go,polyverse-security/go