AT91 MMC update for 2.6.19

The driver is usable on the newer SAM9 processors so replace all text
references to AT91RM9200 with just AT91.

The controller bug where all the words are byte-swapped is fixed on the
AT91SAM9 processors.  The byte-swapping work-around therefore only needs
to be done if cpu_is_at91rm9200().
[Original patch from Wojtek Kaniewski]

The AT91RM9200 and AT91SAM9260 processors support two MMC/SD slots - the
slot which is connected is now passed via the platform_data and the
correct slot selected in the AT91_MCI_SDCR register.

The driver should not be calling at91_set_gpio_output() since the VCC
pin should have already been configured as an output in the
processor/board setup code.  The driver should call
at91_set_gpio_value().

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>