s390/dasd: Rename dasd_raw_build_cp()

Rename dasd_raw_build_cp() to dasd_eckd_build_cp_raw() to fit the
scheme.

Reviewed-by: Stefan Haberland <sth@linux.vnet.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>