spi: Header and core clean up and refactoring

Merge series from Andy Shevchenko <andriy.shevchenko@linux.intel.com>:

Various cleanups and refactorings of the SPI header and core parts
united in a single series. It also touches drivers under SPI subsystem
folder on the pure renaming purposes of some constants.

No functional change intended.

diff --cc drivers/spi/spi-atmel.c
Simple merge

diff --cc drivers/spi/spi-davinci.c
Simple merge

diff --cc drivers/spi/spi-imx.c
Simple merge

diff --cc drivers/spi/spi-stm32.c
index 536d89e044cfbf8c7025845bca8511c284f740f8,423212bd06756ff3e3c1c5ae572a432d79e30109..8cf7b41481b248f57e85ec82fca56946cee5817b
--- 1/drivers/spi/spi-stm32.c
--- 2/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@@ -1752,8 -1750,7 +1752,8 @@@ static const struct stm32_spi_cfg stm32
        .baud_rate_div_min = STM32F4_SPI_BR_DIV_MIN,
        .baud_rate_div_max = STM32F4_SPI_BR_DIV_MAX,
        .has_fifo = false,
-       .flags = SPI_MASTER_MUST_TX,
 +      .has_device_mode = false,
+       .flags = SPI_CONTROLLER_MUST_TX,
  };
  
  static const struct stm32_spi_cfg stm32h7_spi_cfg = {