crypto/nx: Rename nx-842-powernv file name to nx-common-powernv

Rename nx-842-powernv.c to nx-common-powernv.c to add code for setup
and enable new GZIP compression type. The actual functionality is not
changed in this patch.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587114200.2275.1113.camel@hbabu-laptop