hwmon: do not init sensors on startup

The U-Boot Design Principles[1] clearly say:

  Initialize devices only when they are needed within U-Boot, i.e. don't
  initialize the Ethernet interface(s) unless U-Boot performs a download
  over Ethernet; don't initialize any IDE or USB devices unless U-Boot
  actually tries to load files from these, etc. (and don't forget to
  shut down these devices after using them - otherwise nasty things may
  happen when you try to boot your OS).

So, do not initialize and read the sensors on startup.

Signed-off-by: Heiko Schocher <hs@denx.de>
cc: Wolfgang Denk <wd@denx.de>
cc: Holger Brunck <holger.brunck@keymile.com>

arch/powerpc/lib/board.c

@@ -944,9 +944,6 @@ void board_init_r (gd_t *id, ulong dest_addr)
 
 	WATCHDOG_RESET ();
 
-#if defined(CONFIG_DTT)		/* Digital Thermometers and Thermostats */
-	dtt_init ();
-#endif
 #if defined(CONFIG_CMD_SCSI)
 	WATCHDOG_RESET ();
 	puts ("SCSI:  ");