Cleanup the flow of control for rpaphp_add_slot(), so as to
make it easier to read. The ext patch will fix a bug in this 
same code. 
Signed-off-by: NLinas Vepstas <linas@austin.ibm.com>
Cc: John Rose <johnrose@austin.ibm.com>
Signed-off-by: NKristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>