ppc4xx: Clean up 440 exceptions handling

- Introduced dedicated switches for building 440 and 405 images required
  for 440-specific machine instructions like 'rfmci' etc.

- Exception vectors moved to the proper location (_start moved away from
  the critical exception handler space, which it occupied)

- CriticalInput now serviced (with default handler)

- MachineCheck properly serviced (added a dedicated handler and return
  subroutine)

- Overall cleanup of exceptions declared with STD_EXCEPTION macro (unused,
  unhandled and those not relevant for 4xx were eliminated)

- Eliminated Linux leftovers, removed dead code

Signed-off-by: Grzegorz Bernacki <gjb@semihalf.com>
Signed-off-by: Rafal Jaworowski <raj@semihalf.com>
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/include/configs/p3p440.h b/include/configs/p3p440.h
index aa0901f..cae5bd5 100644
--- a/include/configs/p3p440.h
+++ b/include/configs/p3p440.h
@@ -35,6 +35,7 @@
  *----------------------------------------------------------------------*/
 #define CONFIG_P3P440		1	    /* Board is P3P440		*/
 #define CONFIG_440GP		1	    /* Specifc GP support	*/
+#define CONFIG_440		1	    /* ... PPC440 family	*/
 #define CONFIG_4xx		1	    /* ... PPC4xx family	*/
 #define CONFIG_BOARD_EARLY_INIT_F 1	    /* Call board_early_init_f	*/
 #define CONFIG_MISC_INIT_R	1	    /* Call misc_init_r		*/