ARM: don't clone arm_arch_state() code

Have various ARM cores delegate to arm_arch_state() to display
basic information, instead of duplicating that logic.

This shrinks the code, makes them all report when semihosting
is active, and highlights which data are specific to this core.
(Like ARM720 not having separate instruction and data caches.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>