cmd: aprop: fix typo in cast propery->property

While compiling aprop, we have the following warning
  cmd/aprop.c: In function ‘aprop_serialize_to_buf’:
  cmd/aprop.c:215:9: warning: assignment to ‘struct property_field *’ from incompatible pointer type ‘struct propery_field *’ [-Wincompatible-pointer-types]
    field = (struct propery_field *)hdr->data;

Fix it with s/propery_field/property_field

Bug: https://baylibre.atlassian.net/browse/RITA-38
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/cmd/aprop.c b/cmd/aprop.c
index 0d92dc1..4734537 100644
--- a/cmd/aprop.c
+++ b/cmd/aprop.c
@@ -212,7 +212,7 @@
 		hdr->magic = WIRE_TYPE_MULTIPLE;
 		hdr->size = 0;
 
-		field = (struct propery_field *)hdr->data;
+		field = (struct property_field *)hdr->data;
 		field->hdr.magic = WIRE_TYPE_MULTIPLE;
 		field->hdr.size = strlen(aprop.cache[i].key);
 		strncpy(field->string, aprop.cache[i].key, field->hdr.size);