aarch64: don't wait for smp targets halted in deassert reset

aarch64: don't wait for smp targets halted in deassert reset

The function target_type::deassert_reset() is called for every
target after reset is deasserted. If the target fails to get
halted, we log a warning and issue a halt request for the target
itself.

Current code calls the generic target_halt() that:
- extends the halt to all the targets in the SMP node;
- waits for targets to halt.
This breaks the logic of running target_type::deassert_reset()
per target. Plus, waiting for targets to halt delays the call of
target_type::deassert_reset() for the next targets.

Replace the call to target_halt() with the aarch64 specific
function to halt the single target. Pass the parameter HALT_LAZY
to prevent the wait for target halted.
Similar solution is already implemented for cortex_a.

Change-Id: I446dc03cb91524c6d388db485bc2388177af77b6
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6947
Tested-by: jenkins