Store management version info into global variables for easy access

In the future when the mgmtops code needs to behave in different ways
depending on the kernel side management API version it's convenient to
have the exact version/revision number in easily accessible global
variables inside mgmtops.c.
diff --git a/plugins/mgmtops.c b/plugins/mgmtops.c
index 359ecaa..20a9a49 100644
--- a/plugins/mgmtops.c
+++ b/plugins/mgmtops.c
@@ -51,20 +51,23 @@
 static int mgmt_sock = -1;
 static guint mgmt_watch = 0;
 
+static uint8_t mgmt_version = 0;
+static uint16_t mgmt_revision = 0;
+
 static void read_version_complete(int sk, void *buf, size_t len)
 {
 	struct mgmt_hdr hdr;
 	struct mgmt_read_version_rp *rp = buf;
-	uint16_t revision;
 
 	if (len < MGMT_READ_VERSION_RP_SIZE) {
 		error("Too small read version complete event");
 		return;
 	}
 
-	revision = btohs(bt_get_unaligned(&rp->revision));
+	mgmt_revision = btohs(bt_get_unaligned(&rp->revision));
+	mgmt_version = rp->version;
 
-	DBG("version %u revision %u", rp->version, revision);
+	DBG("version %u revision %u", mgmt_version, mgmt_revision);
 
 	memset(&hdr, 0, sizeof(hdr));
 	hdr.opcode = MGMT_OP_READ_INDEX_LIST;