crypto/nx: Create nx842_configure_crb function

Configure CRB is moved to nx842_configure_crb() so that it can
be used for icswx and VAS exec functions. VAS function will be
added later with P9 support.

Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>