arm: socfpga: use imply instead of select where applicable

Kconfig should only 'select' features that are required for an arch.
Standard features that can be disabled without breaking board support
should use 'imply' instead, to allow users to disable it.

These options are changed for mach-socfpga:
- DM_SPI & DM_SPI_FLASH: only required with QSPI support enabled
- SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION: the boot rom supports a
  partitionless mode also, where SPL is located at address 0
- HW_WATCHDOG: while all mainline board defconfigs use it, U-Boot
  should still work without it.

Signed-off-by: Simon Goldschmidt <sgoldschmidt@de.pepperl-fuchs.com>

arch/arm/Kconfig

@@ -698,17 +698,17 @@ config ARCH_SOCFPGA
 	select OF_CONTROL
 	select SPL_OF_CONTROL
 	select DM
-	select DM_SPI_FLASH
-	select DM_SPI
 	select ENABLE_ARM_SOC_BOOT0_HOOK
-	select HW_WATCHDOG
 	select ARCH_EARLY_INIT_R
 	select ARCH_MISC_INIT
-	select SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
 	select SYS_THUMB_BUILD
 	imply CMD_MTDPARTS
 	imply CRC32_VERIFY
+	imply DM_SPI
+	imply DM_SPI_FLASH
 	imply FAT_WRITE
+	imply HW_WATCHDOG
+	imply SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
 
 config ARCH_SUNXI
 	bool "Support sunxi (Allwinner) SoCs"