Change the internal SRAM memory type MT_MEMORY_NONCACHED

Because MT_DEVICE is not executable in armv7, we change
the the internal SRAM memory type to MT_MEMORY_SO as commit
5fe012d4aee98ef82df66e6763882c735902ed0f,
but MT_MEMORY_SO is strongly ordered, this feature is not required
for the internal SRAM memory.

So we change the internal SRAM memory type to MT_MEMORY_NONCACHED.
As it seems that caching this internal SRAM memory is not necessary,
we chose the this memory type.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
pm/ddr: make ddr-sdram enter self refresh mode when excuting pm and cpuidle

Change the implementation of function to be used on other boards with ddr-sdram.

inline void at91sam9g45_standby(void)
==>
inline void at91sam_ddr_standby(unsigned int bank)

Add support to at91sam9x5ek, at91sam9n12ek

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
pm/sama5d3: add pm support for sama5d3xek

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
pm: disable UPLL when excuting PM

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>