[Blackfin] arch: add "memmap=nn[KMG]@ss[KMG]" and "memmap=nn[KMG]$ss[KMG]"...

[Blackfin] arch: add "memmap=nn[KMG]@ss[KMG]" and "memmap=nn[KMG]$ss[KMG]" options to blackfin, based on arch/i386/kernel/e820.c

Signed-off-by: Yi Li <yi.li@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>