arm64: zynqmp: Check 0 node ID

ID is decimal not hexadecimal that's why passing hex number all the time
end's up as 0 that's why check it. Node ID 0 is not valid anyway.
Also properly say it in help.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/68c5cd5eade216f3c5aa6eb703ee9f69f14acad1.1685615549.git.michal.simek@amd.com
diff --git a/board/xilinx/zynqmp/cmds.c b/board/xilinx/zynqmp/cmds.c
index e20030e..c1224bd 100644
--- a/board/xilinx/zynqmp/cmds.c
+++ b/board/xilinx/zynqmp/cmds.c
@@ -216,6 +216,10 @@
 			return zynqmp_pmufw_config_close();
 
 		id = dectoul(argv[3], NULL);
+		if (!id) {
+			printf("Incorrect ID passed\n");
+			return CMD_RET_USAGE;
+		}
 
 		printf("Enable permission for node ID %d\n", id);
 
@@ -429,7 +433,7 @@
 	"		       lock(0)/split(1)\n"
 #endif
 	"zynqmp pmufw address size - load PMU FW configuration object\n"
-	"zynqmp pmufw node <id> - load PMU FW configuration object\n"
+	"zynqmp pmufw node <id> - load PMU FW configuration object, <id> in dec\n"
 	"zynqmp pmufw node close - disable config object loading\n"
 	"	node: keyword, id: NODE_ID in decimal format\n"
 	"zynqmp rsa srcaddr srclen mod exp rsaop -\n"