agp: remove unused variable arqsz in agp_3_5_enable()

This patch fix the following warning:
drivers/char/agp/isoch.c: In function ‘agp_3_5_enable’:
drivers/char/agp/isoch.c:322:13: warning: variable ‘arqsz’ set but not
used [-Wunused-but-set-variable]
  u32 isoch, arqsz;
             ^~~~~
Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/char/agp/isoch.c

@@ -314,7 +314,7 @@ int agp_3_5_enable(struct agp_bridge_data *bridge)
 {
 	struct pci_dev *td = bridge->dev, *dev = NULL;
 	u8 mcapndx;
-	u32 isoch, arqsz;
+	u32 isoch;
 	u32 tstatus, mstatus, ncapid;
 	u32 mmajor;
 	u16 mpstat;
@@ -329,8 +329,6 @@ int agp_3_5_enable(struct agp_bridge_data *bridge)
 	if (isoch == 0)	/* isoch xfers not available, bail out. */
 		return -ENODEV;
 
-	arqsz     = (tstatus >> 13) & 0x7;
-
 	/*
 	 * Allocate a head for our AGP 3.5 device list
 	 * (multiple AGP v3 devices are allowed behind a single bridge).