davinci_cpdma: include linux/module.h

This fixes a number of warnings such as:

  CC      drivers/net/ethernet/ti/davinci_cpdma.o
drivers/net/ethernet/ti/davinci_cpdma.c:279:1: warning: data definition
has no type or storage class
drivers/net/ethernet/ti/davinci_cpdma.c:279:1: warning: type defaults to
‘int’ in declaration of ‘EXPORT_SYMBOL_GPL’
drivers/net/ethernet/ti/davinci_cpdma.c:279:1: warning: parameter names
(without types) in function declaration

Signed-off-by: Daniel Mack <zonque@gmail.com>
Cc: Vaibhav Hiremath <hvaibhav@ti.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>