pflash: bump version to v5.9.4

Bumping to pick up pflash fix
lists.ozlabs.org/pipermail/skiboot/2017-November/009601.html

Change-Id: I23eb1a32c7fde316e1d125eccdced397fb12adab
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
1 file changed