hw/pflash_cfi02: Fix lazy reset of ROMD mode

When checking pfl->rom_mode for when to lazily reenter ROMD mode,
the value was check was the opposite of what it should have been.
This prevent the part from returning to ROMD mode after a write
was made to the CFI rom region.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>