[ARM] 3960/1: AT91: Final SAM9 intergration patches.

This patch includes a number of small changes for integrating the
AT91SAM9261 and AT91SAM0260 support.

      * Can only select support for one AT91 processor at a time.
      * Remove most of the remaining static memory mapping for the
        AT91RM9200.
      * Reserve 1Mb of memory below the IO for mapping the internal SRAM
        and any custom board-specific devices (ie, FPGA).
      * The SAM9260 has more serial ports, so increase the maximum to 7.
      * Define the standard chipselect addresses, and define other
        addresses relative to those.
      * CLOCK_TICK_RATE is different on the SAM926x's.

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