xilinx: Enable CMD_GREPENV/SETEXPR by default

Enable both of these commands in Xilinx SoCs to be able to use them in boot
scripts.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/1a612be7e09e9bc502f30e1f025441ccf8accba5.1661340513.git.michal.simek@amd.com
diff --git a/configs/xilinx_zynqmp_virt_defconfig b/configs/xilinx_zynqmp_virt_defconfig
index e242884..1591f22 100644
--- a/configs/xilinx_zynqmp_virt_defconfig
+++ b/configs/xilinx_zynqmp_virt_defconfig
@@ -57,6 +57,7 @@
 CONFIG_SYS_BOOTM_LEN=0x6400000
 CONFIG_CMD_BOOTMENU=y
 CONFIG_CMD_THOR_DOWNLOAD=y
+CONFIG_CMD_GREPENV=y
 CONFIG_CMD_NVEDIT_EFI=y
 CONFIG_CMD_MEMTEST=y
 CONFIG_SYS_ALT_MEMTEST=y