Compiler warning spots real error!

The function do_rom_fast_read called in do_rom_fast_write can fail
and leave data1 unset. This causes a compile warning.
The correct thing is to propagate the error out.
Signed-off-by: NStephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>