This change allows more fine tuning of driver model based SPI support in
SPL and TPL. It is now possible to explicitly enable/disable the DM_SPI
support in SPL and TPL via Kconfig option.

Before this change it was necessary to use:
    /* SPI Flash Configs */
    #if defined(CONFIG_SPL_BUILD)
    #undef CONFIG_DM_SPI
    #undef CONFIG_DM_SPI_FLASH
    #undef CONFIG_SPI_FLASH_MTD
    #endif

in the ./include/configs/<board>.h, which is error prone and shall be
avoided when we strive to switch to Kconfig.

The goal of this patch:

Provide distinction for DM_SPI support in both U-Boot proper and SPL (TPL).
Valid use case is when U-Boot proper wants to use DM_SPI, but SPL must
still support non DM driver.

Another use case is the conversion of non DM/DTS SPI driver to support
DM/DTS. When such driver needs to work in both SPL and U-Boot proper, the
distinction is needed in Kconfig (also if SPL version of the driver
supports OF_PLATDATA).

In the end of the day one would have to support following use cases (in
single driver file - e.g. mxs_spi.c):

- U-Boot proper driver supporting DT/DTS
- U-Boot proper driver without DT/DTS support (deprecated)
- SPL driver without DT/DTS support
- SPL (and TPL) driver with DT/DTS (when the SoC has enough resources to
  run full blown DT/DTS)
- SPL driver with DT/DTS and SPL_OF_PLATDATA (when one have constrained
  environment with no fitImage and OF_LIBFDT support).

Some boards do require SPI support (with DM) in SPL (TPL) and some only
have DM_SPI{_FLASH} defined to allow compiling SPL.

This patch converts #ifdef CONFIG_DM_SPI* to #if CONFIG_IS_ENABLED(DM_SPI)
and provides corresponding defines in Kconfig.
Signed-off-by: NLukasz Majewski <lukma@denx.de>
Tested-by: Adam Ford <aford173@gmail.com> #da850-evm
Signed-off-by: NHou Zhiqiang <Zhiqiang.Hou@nxp.com>
[trini: Fixup a few platforms]
Signed-off-by: NTom Rini <trini@konsulko.com>