POST: Execute SPR test after relocation

On LWMON5 we now use d-cache as init-ram and stack. The SPR POST test uses
self modifying code and this doesn't work with stack in d-cache, since
I can't move the code from d-cache to i-cache. We move the SPR test to
be executed a little later, after relocation. Then stack is located in
SDRAM and this self-modifying code is no problem anymore.

Signed-off-by: Stefan Roese <sr@denx.de>