fixed an out of range index access

[karman-docker]

Crashing thread - found in docker/for-mac#7588

 panic: runtime error: index out of range [1] with length 1

goroutine 1124 [running]:
github.com/jaypipes/ghw/pkg/cpu.populateSysctlOutput()
github.com/jaypipes/ghw@v0.13.0/pkg/cpu/cpu_darwin.go:87 +0x204
github.com/jaypipes/ghw/pkg/cpu.(*Info).load(0x14001c11260)
github.com/jaypipes/ghw@v0.13.0/pkg/cpu/cpu_darwin.go:17 +0x20
github.com/jaypipes/ghw/pkg/context.(*Context).Do(0x1400038c780, 0x14001f21c58) 
github.com/jaypipes/ghw@v0.13.0/pkg/context/context.go:125 +0x78
github.com/jaypipes/ghw/pkg/cpu.New({0x0?, 0x14000e14100?, 0x2?})

[jaypipes]

👍 thank you for the PR @karman-docker, appreciated! :)