OMAP3: remove unused code from the ASM sleep code

Remove unused code:
- macros,
- variables,
- unused semaphore locking API. This API shall be added back
  when needed,
- infinite loops for debug.

Tested on N900 and Beagleboard with full RET and OFF modes,
using cpuidle and suspend.

Signed-off-by: Jean Pihet <j-pihet@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Tested-by: Nishanth <Menon&lt;nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>