ARM: socfpga: Introduce u-boot-with-nand-spl.sfp target

The NAND devices with 128 kiB erase blocks require extra 64 kiB padding
between each SPL image. Generate U-Boot image with such a padding using
this new target.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Chin Liang See <chin.liang.see@intel.com>
Cc: Dalon Westergreen <dwesterg@gmail.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Cc: Tien Fong Chee <tien.fong.chee@intel.com>
Reviewed-by: Ley Foon Tan <ley.foon.tan@intel.com>
diff --git a/Makefile b/Makefile
index 7485bc2..d3038cf 100644
--- a/Makefile
+++ b/Makefile
@@ -1476,6 +1476,17 @@
 			u-boot.img > $@ || rm -f $@
 u-boot-with-spl.sfp: spl/u-boot-spl.sfp u-boot.img FORCE
 	$(call if_changed,socboot)
+
+quiet_cmd_socnandboot = SOCNANDBOOT $@
+cmd_socnandboot =  dd if=/dev/zero of=spl/u-boot-spl.pad bs=64 count=1024 ; \
+		   cat	spl/u-boot-spl.sfp spl/u-boot-spl.pad \
+			spl/u-boot-spl.sfp spl/u-boot-spl.pad \
+			spl/u-boot-spl.sfp spl/u-boot-spl.pad \
+			spl/u-boot-spl.sfp spl/u-boot-spl.pad \
+			u-boot.img > $@ || rm -f $@ spl/u-boot-spl.pad
+u-boot-with-nand-spl.sfp: spl/u-boot-spl.sfp u-boot.img FORCE
+	$(call if_changed,socnandboot)
+
 endif
 
 ifeq ($(CONFIG_MPC85xx)$(CONFIG_OF_SEPARATE),yy)