net: cwdavinci_cpdma: export symbols for cpsw

With the support for ARM AM33xx in multiplatform kernels
in 3.9, an older bug appears in ARM allmodconfig:
When the cpsw driver is built as a module with cpdma
support enabled, it uses symbols that the cpdma driver
does not export.

Without this patch, building allmodconfig results in:

ERROR: "cpdma_ctlr_int_ctrl" [drivers/net/ethernet/ti/ti_cpsw.ko] undefined!
ERROR: "cpdma_control_set" [drivers/net/ethernet/ti/ti_cpsw.ko] undefined!
ERROR: "cpdma_ctlr_eoi" [drivers/net/ethernet/ti/ti_cpsw.ko] undefined!

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
Cc: Vaibhav Hiremath <hvaibhav@ti.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: netdev@vger.kernel.org