mm: The first 1MB mem is wasted for CPU series coming after TXLX [1/1]

mm: The first 1MB mem is wasted for CPU series coming after TXLX [1/1]

PD#SWPL-3744

Problem:
For the previous Amlogic CPU series(before TXLX), the CPU booting vector
locates at physical address starting from 0x00. To avoid influencing cpu
booting procedure, we have to reserve the first 1MB physical memory. But
it has changed since TXLX, the normal text section can safely use 0~1M
physical address. So it's no need to reserve the first 1MB in DTS.

Solution:
Change the starting address of usable memory from 0x100000 to 0x0 for CPU
series coming after TXLX.

Verify:
Locally on W400

Change-Id: I2df7859a38feca48abd58459e8b231ee15ada9e2
Signed-off-by: changqing.gao <changqing.gao@amlogic.com>