Convert CONFIG_ZYNQMP_PSU_INIT_ENABLED to Kconfig

This converts the following to Kconfig:
   CONFIG_ZYNQMP_PSU_INIT_ENABLED

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/xilinx_zynqmp_mini_nand_single_defconfig b/configs/xilinx_zynqmp_mini_nand_single_defconfig
index 723c611..13a479f 100644
--- a/configs/xilinx_zynqmp_mini_nand_single_defconfig
+++ b/configs/xilinx_zynqmp_mini_nand_single_defconfig
@@ -7,6 +7,7 @@
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_ENV_SIZE=0x80
 CONFIG_DEFAULT_DEVICE_TREE="zynqmp-mini-nand"
+CONFIG_ZYNQMP_PSU_INIT_ENABLED=y
 # CONFIG_CMD_ZYNQMP is not set
 CONFIG_SYS_LOAD_ADDR=0x8000000
 CONFIG_FIT=y