ARM: OMAP4: Remove un-used do_wfi() macro.

With OMAP4 suspend, idle and hotplug series, we no longer need
do_wfi() macro.

Remove the same.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Jean Pihet <j-pihet@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>