Move the entire NX-842 driver for the pSeries platform from the file
nx-842.c to nx-842-pseries.c.  This is required by later patches that
add NX-842 support for the PowerNV platform.

This patch does not alter the content of the pSeries NX-842 driver at
all, it only changes the filename.
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>