arc: fix CONFIG_ARC_STACK_CHECKING

- There's no clear need to disable frame pointers if this feature is
used, remove this directive.
- The 'top' and 'base' terms are reversed. The 'base' is the high
address of the stack. The top is the lowest address, where we cannot
push further down. Fixup member and offset names to correspond to how
these terms are used in hardware documentation.
- Use correct pointers for stack top location
- Fatal exceptions now go through _NanoFatalErrorHandler to report the
faulting ip and thread.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>