USB: ehci-dbg: fix reading less content of periodic file

This patch fix 2 problems about reading periodic file:

1. The "..." after a interrupt qh is missed because buffer pointer is
   not moved.

2. After setting p.ptr as NULL, its next qh or itd will be omited and
   can't be stored in debug buffer.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/host/ehci-dbg.c b/drivers/usb/host/ehci-dbg.c
index 9534ff3..5d57773 100644
--- a/drivers/usb/host/ehci-dbg.c
+++ b/drivers/usb/host/ehci-dbg.c
@@ -569,14 +569,16 @@
 				for (temp = 0; temp < seen_count; temp++) {
 					if (seen [temp].ptr != p.ptr)
 						continue;
-					if (p.qh->qh_next.ptr)
+					if (p.qh->qh_next.ptr) {
 						temp = scnprintf (next, size,
 							" ...");
-					p.ptr = NULL;
+						size -= temp;
+						next += temp;
+					}
 					break;
 				}
 				/* show more info the first time around */
-				if (temp == seen_count && p.ptr) {
+				if (temp == seen_count) {
 					u32	scratch = hc32_to_cpup(ehci,
 							&p.qh->hw_info1);
 					struct ehci_qtd	*qtd;