mksys: change lui to li for system calls

I got this wrong the first time around.

Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>

Conflicts:
	util/src/harvey/cmd/mksys/mksys.go

util/src/harvey/cmd/mksys/mksys.go

@@ -201,7 +201,7 @@ TEXT runtime·{{ .Libname }}(SB),NOSPLIT,$0
 		tmpl, err = template.New("syscall.s").Parse(`/* automatically generated by mksys */
 .globl	{{ .Libname }}
 {{ .Libname }}:
-	/*movq ${{ .Id }},%rax  * Put the system call into rax, just like linux. */
+	li a7, {{ .Id }}  /* Put the system call into a7 so we don't have to move a0-a6 around*/
 	scall
 	ret
 `)