Add silicon revision "any" and "none". Add proper -mcpu option according
to the cpu and silicon revision configuration.

Need update to use latest Blackfin cross compile toolchain.
Signed-off-by: NJie Zhang <jie.zhang@analog.com>
Signed-off-by: NMike Frysinger <michael.frysinger@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>