xilinx: Return ENVL_NOWHERE instead of ENVL_UNKNOWN

The system refuses to boot without any environment, so return ENVL_NOWHERE when
there's nowhere to store the environment instead of ENVL_UNKNOWN.

This fixes that the board won't boot from eMMC when CONFIG_ENV_IS_IN_FAT is not
defined, for example. Similar for other combinations.

Fixes: 1025bd098aa8 "xilinx: zynqmp: Add support for saving variables"

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/zynq/board.c b/board/xilinx/zynq/board.c
index e2e9b3f..61e0a90 100644
--- a/board/xilinx/zynq/board.c
+++ b/board/xilinx/zynq/board.c
@@ -134,18 +134,18 @@
 			return ENVL_FAT;
 		if (IS_ENABLED(CONFIG_ENV_IS_IN_EXT4))
 			return ENVL_EXT4;
-		return ENVL_UNKNOWN;
+		return ENVL_NOWHERE;
 	case ZYNQ_BM_NAND:
 		if (IS_ENABLED(CONFIG_ENV_IS_IN_NAND))
 			return ENVL_NAND;
 		if (IS_ENABLED(CONFIG_ENV_IS_IN_UBI))
 			return ENVL_UBI;
-		return ENVL_UNKNOWN;
+		return ENVL_NOWHERE;
 	case ZYNQ_BM_NOR:
 	case ZYNQ_BM_QSPI:
 		if (IS_ENABLED(CONFIG_ENV_IS_IN_SPI_FLASH))
 			return ENVL_SPI_FLASH;
-		return ENVL_UNKNOWN;
+		return ENVL_NOWHERE;
 	case ZYNQ_BM_JTAG:
 	default:
 		return ENVL_NOWHERE;