staging: ozwpan: Fix build warning.

This patch fixes following build warning.

drivers/built-in.o: In function `oz_hcd_heartbeat':
>> (.text+0x30aadd): undefined reference to `__divdi3'
   drivers/built-in.o: In function `oz_hcd_heartbeat':
>> (.text+0x30ac85): undefined reference to `__divdi3'

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Rupesh Gujare <rupesh.gujare@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>