Display FUSB302 ID register on probe failure

Signed-off-by: Marc Zyngier <maz@kernel.org>

vdmtool.c

diff --git a/vdmtool.c b/vdmtool.c
index ae3abec..18344d7 100644
--- a/vdmtool.c
+++ b/vdmtool.c
@@ -677,7 +677,7 @@
 
 	tcpc_read(PORT(cxt), TCPC_REG_DEVICE_ID, &reg);
 	if (!(reg & 0x80)) {
-		cprintf(cxt, "Invalid device ID. Is the FUSB302 alive?\n");
+		cprintf(cxt, "Invalid device ID %04x. Is the FUSB302 alive?\n", reg);
 		cxt->hw = NULL;
 		return;
 	}