arm64: zynqmp: Add support for OF_SEPARATE with board DTB

OF_BOARD and OF_SEPARATE can use board specific board_fdt_blob_setup().

OF_BOARD option is mostly used for picking up DTB from certain location.

OF_SEPARATE option is used when DTB is appended after u-boot binary.

This board specific function is aligned with current version in
lib/fdtdec.c with checking CONFIG_XILINX_OF_BOARD_DTB_ADDR address first.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/Kconfig b/board/xilinx/Kconfig
index 7833b11..73fc1be 100644
--- a/board/xilinx/Kconfig
+++ b/board/xilinx/Kconfig
@@ -44,7 +44,7 @@
 	hex
 	default 0x1000 if ARCH_VERSAL
 	default 0x100000 if ARCH_ZYNQ || ARCH_ZYNQMP
-	depends on OF_BOARD
+	depends on OF_BOARD || OF_SEPARATE
 	help
 	  Offset in the memory where the board configuration DTB is placed.