ARM: socfpga: Build sfp image only for Gen5 and Arria10 devices

The sfp file is only valid for Gen5 (Cyclone5 & Arria5) and Arria10
devices.  The file should only be built for these devices.
Signed-off-by: NDalon Westergreen <dalon.westergreen@intel.com>

Kconfig

@@ -226,7 +226,8 @@ config BUILD_ROM
 
 config BUILD_TARGET
 	string "Build target special images"
-	default "u-boot-with-spl.sfp" if ARCH_SOCFPGA
+	default "u-boot-with-spl.sfp" if TARGET_SOCFPGA_ARRIA10
+	default "u-boot-with-spl.sfp" if TARGET_SOCFPGA_GEN5
 	default "u-boot-spl.kwb" if ARCH_MVEBU && SPL
 	default "u-boot-elf.srec" if RCAR_GEN3
 	default "u-boot.itb" if SPL_LOAD_FIT && ARCH_SUNXI

scripts/Makefile.spl

@@ -212,7 +212,7 @@ ifdef CONFIG_SAMSUNG
 ALL-y	+= $(obj)/$(BOARD)-spl.bin
 endif
 
-ifdef CONFIG_ARCH_SOCFPGA
+ifneq ($(CONFIG_TARGET_SOCFPGA_GEN5)$(CONFIG_TARGET_SOCFPGA_ARRIA10),)
 ALL-y	+= $(obj)/$(SPL_BIN).sfp
 endif