Revert "arch: arm: cortex_m: restore comment lost in translation"

	/* restore mode */

	IF_ENABLED(CONFIG_USERSPACE, ({

			   CONTROL_Type ctrl = {.w = __get_CONTROL()};

			/* exit privileged state when returning to thread mode. */

			   /* exit privileged state when returing to thread mode. */

			   ctrl.b.nPRIV = 0;

			/* __set_CONTROL inserts an ISB which is may not be necessary here

			 * (stack pointer may not be touched), but it's recommended to avoid

			 * executing pre-fetched instructions with the previous privilege.

			 */

			   __set_CONTROL(ctrl.w | current->arch.mode);

		   }));