crypto: ccp - Make function ccp_get_dma_chan_attr static

Function ccp_get_dma_chan_attr is local to the source and does not
need to be in global scope, so make it static.

Cleans up sparse warning:
drivers/crypto/ccp/ccp-dmaengine.c:41:14: warning: symbol
'ccp_get_dma_chan_attr' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>