[ARM] 4151/1: AT91 / AVR32: Move at91_pdc.h to linux/atmel_pdc.h

The Atmel AT91 and AVR32 processor architectures share many of the same
peripherals.  The PDC (Peripheral Data Controller) registers are also
implemented within in a number of the on-chip peripherals (eg, USART,
MMC, SPI, SSC, etc).

In a attempt not to duplicate the register definitions in each
peripheral, or in each architecture, the at91_pdc.h header in
asm-arm/arch-at91 and asm-avr32/arch-at32ap has been replaced with
linux/atmel_pdc.h.

The definitions have also been renamed from AT91_PDC_* to ATMEL_PDC_*,
and the drivers updated accordingly.

Original patch from Nicolas Ferre.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>