[PATCH resend] arm:extend the reserved memory for initrd to be page aligned

[Wang, Yalin]

> Who guarantees there's no valuable data in [start, initrd_start) and
> [initrd_end, end) being corrupted?
> 
mm..
I am not sure if the memblock_reserve will reserve
Memory from page aligned address?
If not, do we need also make memblock_reserve the initrd memory
From page aligned start(round down) to page aligned end address(round up) ? 

Thanks