net: cavium: fix driver name

The driver name gets exposed in sysfs under /sys/bus/pci/drivers
so it should look like other devices. Change it to be common
format (instead of "Cavium PTP").

This is a trivial fix that was observed by accident because
Debian kernels were building this driver into kernel (bug).
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/common/cavium_ptp.c

@@ -10,7 +10,7 @@
 
 #include "cavium_ptp.h"
 
-#define DRV_NAME	"Cavium PTP Driver"
+#define DRV_NAME "cavium_ptp"
 
 #define PCI_DEVICE_ID_CAVIUM_PTP	0xA00C
 #define PCI_DEVICE_ID_CAVIUM_RST	0xA00E