cfi: use ARM32 machine code on all CPUs but Cortex M3

cfi: use ARM32 machine code on all CPUs but Cortex M3

ARM11 broke with aa61a3b3d8b6acad19050987835ec05f3d298bdb
as the code only checked for arm 7/9.

CFI probably needs work for non-ARM targets but perhaps
not adding working area memory to e.g. MIPS will give
the default slow CFI support.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>