firmware: invert conditions to reduce depth
firmware: invert conditions to reduce depth

Invert the conditions to reduce future depth.  Not an issue now, but
easily could head in that direction.

Change-Id: Id02c839c608af945a6b2311d44447266bf112904
Signed-off-by: Patrick Venture <36c53fa43f47f3fd67cb2fc38031827244d18a1f@google.com>

openbmc/phosphor-ipmi-flash