ARM: add arm_mode_name()

ARM: add arm_mode_name()

Add and use arm_mode_name() to map from PSR bits to user
meaningful names.   It uses a new table which, later, can
be used to hold other mode-coupled data.

Add definitions for the "Secure Monitor" mode, as seen on
some ARM11 cores (like ARM1176) and on Cortex-A8.  The
previous mode name scheme didn't understand that mode.

Remove the old mechanism ... there were two copies, caused
by Cortex-A8 needing to add "Secure Monitor" mode support.

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