u-boot-xlnx-uenv: Add missing space to append operation

Based on github Pull Request #42.  While that pull request is no longer
valid with other changes, the actual bug still exists.

Originally reported by AnatoliiShablov.

Signed-off-by: Mark Hatle <mark.hatle@amd.com>
(cherry picked from commit 0812624)
Signed-off-by: Mark Hatle <mark.hatle@amd.com>

Author: mhatle

meta-xilinx-core/recipes-bsp/u-boot/u-boot-xlnx-uenv.bb

@@ -79,7 +79,7 @@ def uenv_populate(d):
 
     return env
 
-DEPENDS:append := "virtual/kernel ${@remove_task_from_depends(d)}"
+DEPENDS:append := " virtual/kernel ${@remove_task_from_depends(d)}"
 
 # bootargs, default to booting with the rootfs device being partition 2
 KERNEL_BOOTARGS:zynq = "earlyprintk console=ttyPS0,115200 root=/dev/mmcblk0p2 rw rootwait"