staging: ccree: simplify registers access

The register offset calculation macro was taking a HW block base
parameter that was not actually used. Simplify the whole thing
by dropping it and rename the macro for better readability.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>