net: cdc_ncm: fix 64bit division build error

The upper timer_interval limit is arbitrary and much higher
than anything usable in the real world.  Reducing it from 15s
to ~4s to make the timer_interval fit in an u32 does not make
much difference.  The limit is still outside the practical
bounds.

This eliminates the need for a 64bit timer_interval, fixing a
build error related to 64bit division:

 drivers/built-in.o: In function `cdc_ncm_get_coalesce':
 ak8975.c:(.text+0x1ac994): undefined reference to `__aeabi_uldivmod'

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/usb/cdc_ncm.h b/include/linux/usb/cdc_ncm.h
index 8c5e388..7c9b484 100644
--- a/include/linux/usb/cdc_ncm.h
+++ b/include/linux/usb/cdc_ncm.h
@@ -78,7 +78,7 @@
 #define	CDC_NCM_TIMER_PENDING_CNT		2
 #define CDC_NCM_TIMER_INTERVAL_USEC		400UL
 #define CDC_NCM_TIMER_INTERVAL_MIN		5UL
-#define CDC_NCM_TIMER_INTERVAL_MAX		(15UL * USEC_PER_SEC)
+#define CDC_NCM_TIMER_INTERVAL_MAX		(U32_MAX / NSEC_PER_USEC)
 
 #define cdc_ncm_comm_intf_is_mbim(x)  ((x)->desc.bInterfaceSubClass == USB_CDC_SUBCLASS_MBIM && \
 				       (x)->desc.bInterfaceProtocol == USB_CDC_PROTO_NONE)
@@ -104,7 +104,7 @@
 	spinlock_t mtx;
 	atomic_t stop;
 
-	u64 timer_interval;
+	u32 timer_interval;
 	u32 max_ndp_size;
 
 	u32 tx_timer_pending;