ARM: at91/dt: at91sam9263: Fixup sram1 device tree node

Commit ff04660e48b20 ("ARM: at91/dt: add SRAM nodes") used the same base
address for sram0 and sram1 leading to the following warning:
WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x50/0x70()
sysfs: cannot create duplicate filename '/devices/platform/300000.sram'
Fix the base address for sram1.

Signed-off-by: Alexander Stein <alexanders83@web.de>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>