external/pflash: Make MTD accesses the default
external/pflash: Make MTD accesses the default

Now that BMC and host kernel mtd drivers exist and have matured we
should use them by default.

This is especially important since we seem to be telling everyone to use
pflash.

Signed-off-by: Cyril Bur <6ce38dade8c4b52fd55c193fae70fd1d1275c3c3@au1.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

open-power/skiboot,mikey/skiboot,open-power/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,stewart-ibm/skiboot,qemu/skiboot,stewart-ibm/skiboot,qemu/skiboot,legoater/skiboot,mikey/skiboot,qemu/skiboot,legoater/skiboot,qemu/skiboot,mikey/skiboot,shenki/skiboot,shenki/skiboot,shenki/skiboot,open-power/skiboot,legoater/skiboot,shenki/skiboot,qemu/skiboot,legoater/skiboot,stewart-ibm/skiboot