Driver for the Atmel on-chip SSC on AT32AP and AT91

The Synchronous Serial Controller (SSC) on Atmel microprocessors are
capable of tranceiving many frame based protocols, like I2S.  Tested on the
AT32AP7000/ATSTK1000.

This driver is used in the ALSA sound driver for the AT73C213 external DAC
on the ATSTK1000 development board for AVR32.  This sound driver will be
submitted soon.

Hardware documentation can be found in the AT32AP7000 data sheet, which can
be downloaded from
http://www.atmel.com/dyn/products/datasheets.asp?family_id=682

[akpm@linux-foundation.org: init spinlock at compile time]
Signed-off-by: Hans-Christian Egtvedt <hcegtvedt@atmel.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Andrew Victor <andrew@sanpeople.com>
Cc: Patrice Vilchez <patrice.vilchez@rfo.atmel.com>
Cc: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>