runtime/cgo: fix callback on big-endian MIPS64
runtime/cgo: fix callback on big-endian MIPS64

Use MOVW, instead of MOVV, to pass an int32 arg. Also no need to
restore arg registers.

Fix big-endian MIPS64 build.

Change-Id: Ib43c71075c988153e5e5c5c6e7297b3fee28652a
Reviewed-on: https://go-review.googlesource.com/28830
Reviewed-by: Minux Ma <72d850dbd8858b791995463d8539b5a379577f28@golang.org>

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