spi: add driver for Freescale QSPI controller ...

This is based on the Linux v5.1-rc1 driver introduced with the commit:

  commit 84d0431
  Refs: v5.0-rc1-1-g84d043185dbe
  Author:     Frieder Schrempf <frieder.schrempf@kontron.de>
  AuthorDate: Mon Jan 7 09:29:47 2019 +0000
  Commit:     Mark Brown <broonie@kernel.org>
  CommitDate: Mon Jan 7 16:56:24 2019 +0000

      spi: Add a driver for the Freescale/NXP QuadSPI controller

      This driver is derived from the SPI NOR driver at
      mtd/spi-nor/fsl-quadspi.c. It uses the new SPI memory interface
      of the SPI framework to issue flash memory operations to up to
      four connected flash chips (2 buses with 2 CS each).

      The controller does not support generic SPI messages.

      This patch also disables the build of the "old" driver and reuses
      its Kconfig option CONFIG_SPI_FSL_QUADSPI to replace it.

      Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
      Acked-by: Han Xu <han.xu@nxp.com>
      Reviewed-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
      Tested-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
      Tested-by: Han Xu <han.xu@nxp.com>
      Reviewed-by: Boris Brezillon <bbrezillon@kernel.org>
      Signed-off-by: Mark Brown <broonie@kernel.org>

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>