arm64: zynqmp: Enable cache command

Sometimes it is very useful to be able disable/enable cache that's why
enable commands for it by default.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/xilinx_zynqmp_virt_defconfig b/configs/xilinx_zynqmp_virt_defconfig
index 5b4fe53..8ffcd3d 100644
--- a/configs/xilinx_zynqmp_virt_defconfig
+++ b/configs/xilinx_zynqmp_virt_defconfig
@@ -50,6 +50,7 @@
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_MASS_STORAGE=y
 CONFIG_CMD_TFTPPUT=y
+CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIME=y
 CONFIG_CMD_TIMER=y
 CONFIG_CMD_EXT4_WRITE=y