powerpc/config: powernv_defconfig updates

powerpc/config: powernv_defconfig updates

For consideration:

* Add NVDIMM support - Enables greater testing, mambo device.
* Add IPv6 support built in + additional modules - Because it's 2018 maan.
* Add DEFERRED_STRUCT_PAGE_INIT - Let's see what breaks.
* Add PPC_MEMTRACE - Small powernv debugfs driver for getting hardware traces.
* Add MEMORY_FAILURE - Machine check exceptions can now drive memory failure.
* Turn on FANOTIFY - This is the current filesystem notification feature.
* Turn on SCOM_DEBUGFS - Handy for hardware/firmware debugging, security risk?
* Turn on async SCSI scanning - Let's see what breaks.
* Add MLX5 driver as a module - Popular demand.
* Add CRYPTO_CRCT10DIF_VPMSUM - POWER8 T10DIF acceleration.

* Make a bunch of USB hid drivers modules.
* Make SCSI SG, SR, and FC modules - FC is huge.
* Make video drivers except AST GPU modules - Also huge.
* Make PCI serial driver a module - Uncommon.
* Make more things modules, NFS FS, RAM disk, netconsole, MS-DOS fs.

* Get rid of /dev/port - Not used.
* Remove PPS and PTP subsystms - Unusual.
* Remove legacy BSD ttys - Long dead.
* Remove IDE - Deprecated and replaced with ATA.
* Remove WIRELESS - Until we get POWER9 laptops.
* Remove RAW - Long deprecated in favour of direct IO.
* Remove floppy, parport, and PS2 input devices - not supported.
* Remove virtio drivers, ballooning - We're host only.
* Remove PPP - Sorry Paulus.

This results in a significantly smaller vmlinux:

    text      data       bss        dec   filename
13143383   5277944   1317856   19739183   vanilla
12263281   4852074   1341720   18457075   patched

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>