MIPS: Fix unable to reserve memory for Crash kernel

Use 0 as the align parameter in memblock_find_in_range() is
incorrect when we reserve memory for Crash kernel.

The environment as follows:
[    0.000000] MIPS: machine is loongson,loongson64c-4core-rs780e
...
[    1.951016]     crashkernel=64M@128M

The warning as follows:
[    0.000000] Invalid memory region reserved for crash kernel

And the iomem as follows:
00200000-0effffff : System RAM
  04000000-0484009f : Kernel code
  048400a0-04ad7fff : Kernel data
  04b40000-05c4c6bf : Kernel bss
1a000000-1bffffff : pci@1a000000
...

The align parameter may be finally used by round_down() or round_up().
Like the following call tree:

mips-next: mm/memblock.c

memblock_find_in_range
└── memblock_find_in_range_node
    ├── __memblock_find_range_bottom_up
    │   └── round_up
    └── __memblock_find_range_top_down
        └── round_down
\#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
\#define round_down(x, y) ((x) & ~__round_mask(x, y))
\#define __round_mask(x, y) ((__typeof__(x))((y)-1))

The round_down(or round_up)'s second parameter must be a power of 2.
If the second parameter is 0, it both will return 0.

Use 1 as the parameter to fix the bug and the iomem as follows:
00200000-0effffff : System RAM
  04000000-0484009f : Kernel code
  048400a0-04ad7fff : Kernel data
  04b40000-05c4c6bf : Kernel bss
  08000000-0bffffff : Crash kernel
1a000000-1bffffff : pci@1a000000
...

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>