This patch cloned most of the m25p80.c. In theory, it adds a new spi-nor layer.

Before this patch, the layer is like:

                   MTD
         ------------------------
                  m25p80
         ------------------------
	       spi bus driver
         ------------------------
	        SPI NOR chip

After this patch, the layer is like:
                   MTD
         ------------------------
                  spi-nor
         ------------------------
                  m25p80
         ------------------------
	       spi bus driver
         ------------------------
	       SPI NOR chip

With the spi-nor controller driver(Freescale Quadspi), it looks like:
                   MTD
         ------------------------
                  spi-nor
         ------------------------
                fsl-quadspi
         ------------------------
	       SPI NOR chip

New APIs:
   spi_nor_scan: used to scan a spi-nor flash.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Acked-by: NMarek Vasut <marex@denx.de>
[Brian: rebased to include additional m25p_ids[] entry]
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

The spi_nor{} is cloned from the m25p{}.
The spi_nor{} can be used by both the m25p80 and spi-nor controller.

We also add the spi_nor_xfer_cfg{} which can be used by the two
fundamental primitives: read_xfer/write_xfer.

 1) the hooks for spi_nor{}:
    @prepare/unpreare: used to do some work before or after the
             read/write/erase/lock/unlock.
    @read_xfer/write_xfer: We can use these two hooks to code all
             the following hooks if the driver tries to implement them
             by itself.
    @read_reg: used to read the registers, such as read status register,
             read configure register.
    @write_reg: used to write the registers, such as write enable,
             erase sector.
    @read_id: read out the ID info.
    @wait_till_ready: wait till the NOR becomes ready.
    @read: read out the data from the NOR.
    @write: write data to the NOR.
    @erase: erase a sector of the NOR.

 2) Add a new field sst_write_second for the SST NOR write.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Acked-by: NMarek Vasut <marex@denx.de>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

This patch adds a new header :spi-nor.h,
and copies all the SPI NOR commands and relative macros into this new header.

This hearder can be used by the m25p80.c and other spi-nor controller,
such as Freescale's Quadspi.
Signed-off-by: NHuang Shijie <b32955@freescale.com>
Acked-by: NMarek Vasut <marex@denx.de>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>