altera: update use of BR2_TARGET_UBOOT_PATCH_DIR

Use BR2_TARGET_UBOOT_PATCH now that BR2_TARGET_UBOOT_PATCH_DIR is
deprecated.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

configs/altera_sockit_defconfig

@@ -31,7 +31,7 @@ BR2_TARGET_UBOOT_BOARDNAME="socfpga_cyclone5"
 BR2_TARGET_UBOOT_CUSTOM_GIT=y
 BR2_TARGET_UBOOT_CUSTOM_REPO_URL="git://git.rocketboards.org/u-boot-socfpga.git"
 BR2_TARGET_UBOOT_CUSTOM_REPO_VERSION="rel_acds13.0sp1"
-BR2_TARGET_UBOOT_CUSTOM_PATCH_DIR="board/altera/sockit"
+BR2_TARGET_UBOOT_PATCH="board/altera/sockit"
 BR2_TARGET_UBOOT_FORMAT_IMG=y
 BR2_TARGET_UBOOT_SPL=y
 BR2_TARGET_UBOOT_SPL_NAME="spl/u-boot-spl.bin"