A number of cleanup items related to the PSP memory range API

- Make the table itself an internal object - should only be accessed
via the PSP API.
- Update to use size_t instead of uint32
- Update the Linux/RTEMS implementation to use full range (SIZE_MAX).

This global config structure is not really necessary.  The original
intent was to allow dependents (e.g. CFE) to get vars at runtime but
keep them stored within PSP.  However for all those cases where CFE
needs PSP info, an API function is defined to get the info.  There
should not be any need to read this variable directly.

Fix #280, remove psp configdata global object

Fix #281, cleanup memory range table