Replace hlt with halt()

There were instances of unneeded arch/hlt.h includes,
various hlt() calls that weren't supposed to exit (but
might have) and various forms of endless loops around
hlt() calls.

All these are sorted out now: unnecessary includes are
dropped, hlt() is uniformly replaced with halt() (except
in assembly, obviously).

Change-Id: I3d38fed6e8d67a28fdeb17be803d8c4b62d383c5
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: http://review.coreboot.org/7608
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/soc/nvidia/tegra124/bootblock.c

@@ -18,7 +18,6 @@
  */
 
 #include <arch/exception.h>
-#include <arch/hlt.h>
 #include <bootblock_common.h>
 #include <cbfs.h>
 #include <console/console.h>