Crypto: atmel-ecc: Make a couple of local functions static

Functions atmel_ecc_i2c_client_alloc and atmel_ecc_i2c_client_free are
local to the source and no not need to be in the global scope. Make
them static.

Cleans up sparse warnings:
symbol 'atmel_ecc_i2c_client_alloc' was not declared. Should it be static?
symbol 'atmel_ecc_i2c_client_free' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>