crypto/nx: Add P9 NX support for 842 compression engine

This patch adds P9 NX support for 842 compression engine. Virtual
Accelerator Switchboard (VAS) is used to access 842 engine on P9.

For each NX engine per chip, setup receive window using
vas_rx_win_open() which configures RxFIFo with FIFO address, lpid,
pid and tid values. This unique (lpid, pid, tid) combination will
be used to identify the target engine.

For crypto open request, open send window on the NX engine for
the corresponding chip / cpu where the open request is executed.
This send window will be closed upon crypto close request.

NX provides high and normal priority FIFOs. For compression /
decompression requests, we use only hight priority FIFOs in kernel.

Each NX request will be communicated to VAS using copy/paste
instructions with vas_copy_crb() / vas_paste_crb() functions.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/crypto/nx/Kconfig

@@ -38,6 +38,7 @@ config CRYPTO_DEV_NX_COMPRESS_PSERIES
 config CRYPTO_DEV_NX_COMPRESS_POWERNV
 	tristate "Compression acceleration support on PowerNV platform"
 	depends on PPC_POWERNV
+	depends on PPC_VAS
 	default y
 	help
 	  Support for PowerPC Nest (NX) compression acceleration. This