pyramid: Re-map memory to use 4 memory banks

*Changed kernel start address to 0x40400000
*Removed Ion writeback heap (MSM8660 doesn't use writeback)
*Userspace has 620MB of RAM as seen in About phone
*Removed writeback code (MSM8660 doesn't support writeback)
Signed-off-by: Sultanxda <sultanxda@gmail.com>