mtd: st_spi_fsm: Supply the N25Qxxx chip specific configuration call-back

In the FSM driver we handle chip differences by providing the possibility
of calling back into a chip specific initialisation routine. In this patch
we provide one for the N25Qxxx series, which endeavours to setup things
like the read, write and erase sequences, as they differ from the
default. We also configure 32bit support and the amount of dummy cycles to
use.

Acked-by Angus Clark <angus.clark@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>