spi: Move DM_SPI_FLASH to Kconfig (for NXP's ls1043a)

This patch fixes issue with defining the DM_SPI_FLASH in the
configs/include/<board.h> instead of enabling this option in Kconfig.

The problem is that CONFIG_IS_ENABLED(DM_SPI_FLASH) shows false as there
is no DM_SPI_FLASH=y in .config (but the define is set in u-boot.cfg).

As a result conversion of DM_SPI_FLASH to using CONFIG_IS_ENABLED() is not
working properly.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 73a2731..714c81e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1510,6 +1510,8 @@
 	select BOARD_LATE_INIT
 	select SUPPORT_SPL
 	select FSL_DDR_INTERACTIVE if !SPL
+	select FSL_DSPI if !SPL_NO_DSPI
+	select DM_SPI_FLASH if FSL_DSPI
 	imply SCSI
 	imply SCSI_AHCI
 	help
@@ -1524,6 +1526,8 @@
 	select BOARD_EARLY_INIT_F
 	select BOARD_LATE_INIT
 	select SUPPORT_SPL
+	select FSL_DSPI if !SPL_NO_DSPI
+	select DM_SPI_FLASH if FSL_DSPI
 	help
 	  Support for Freescale LS1043ARDB platform.