mtd: eLBC NAND: give more verbose output on error

We want error information even if the kernel hasn't been built for verbose
debugging.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>