We found that the original implementation will only use the built-in dtb
pointer instead of the pointer pass from bootloader. This bug is fixed
by this patch.

Signed-off-by: Greentime Hu <greentime@andestech.com>

We use tlbop to map virtual address in the first beginning, however it
may map too much if DRAM size is not that big. We have to invalidate the
mapping when the page table is created.

Signed-off-by: Greentime Hu <greentime@andestech.com>

This patch includes the kernel startup code. It can get dtb pointer
passed from bootloader. It will create a temp mapping by tlb
instructions at beginning and goto start_kernel.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>