core/flash: Ignore prefix when comparing versions.
core/flash: Ignore prefix when comparing versions.

The Skiboot version can include a "skiboot-" prefix if built with
something like Buildroot. The property being compared against won't
include this so ignore it.

Signed-off-by: Samuel Mendoza-Jonas <f16bed56189e249fe4ca8ed10a1ecae60e8ceac0@mendozajonas.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.ibm.com>

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