mtd: m25p80: Add support for Macronix 25L8005

Add support for Macronix 25L8005.  Tested on a HP t5325 Thin Client.

Signed-off-by: Martin Michlmayr <tbm@cyrius.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>