mtd: generic FSMC NAND MTD driver

This is the same driver submitted by ST Micros SPEAr team but
generalized and tested on the ST-Ericsson U300. It probably
easily works on the NHK8815 too.

Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Rajeev Kumar <rajeev-dlh.kumar@st.com>
Signed-off-by: Shiraz Hashim <shiraz.hashim@st.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>