nand/denali: move all hardware initialization work to denali_hw_init

All hardware initialization will be done in denali_hw_init before
irq handler registered
Change mtd name from "DENALI NAND" to be "denali-nand" since whitespace in
name can cause problems if we use cmdlinepart

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>