Cache phandle of /chosen
Cache phandle of /chosen

We constantly access /chosen, among other in the console I/O routines
so instead of doing a path walk every time, cache the phandle

Signed-off-by: Benjamin Herrenschmidt <a7089bb6e7e92505d88aaff006cbdd60cc9120b6@kernel.crashing.org>

dgibson/SLOF,agraf/SLOF,leilihh/SLOF,aik/SLOF,agraf/SLOF,open-power-host-os/slof,qemu/SLOF,leilihh/SLOF,aik/SLOF,agraf/SLOF,dgibson/SLOF,mdroth/SLOF,stefanberger/SLOF-tpm,open-power-host-os/slof,open-power-host-os/slof,k0da/SLOF,aik/SLOF,qemu/SLOF,k0da/SLOF,dgibson/SLOF,agraf/SLOF,stefanberger/SLOF-tpm,leilihh/SLOF,leilihh/SLOF,k0da/SLOF,qemu/SLOF,dgibson/SLOF,mdroth/SLOF,stefanberger/SLOF-tpm,open-power-host-os/slof,k0da/SLOF,mdroth/SLOF,mdroth/SLOF