ACPICA: Switch back to using strncpy() in acpi_ut_safe_strncpy()

ACPICA commit b90d0d65ec97ff8279ad826f4102e0d31c5f662a

I mistakenly replaced strncpy() with memcpy() in commit ebf27765
("ACPICA: Replace strncpy() with memcpy()"), not realizing the entire
context behind *why* strncpy() was used.

In this safer implementation of strncpy(), it does not make
sense to use memcpy() only to null-terminate strings passed to
acpi_ut_safe_strncpy() one byte early.

The consequences of doing so are understandably *bad*, as was
evident by the kernel test bot reporting problems [1].

Fixes: ebf27765 ("ACPICA: Replace strncpy() with memcpy()")
Link: https://lore.kernel.org/all/202505081033.50e45ff4-lkp@intel.com

 [1]
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202505081033.50e45ff4-lkp@intel.com
Link: https://github.com/acpica/acpica/commit/b90d0d65


Signed-off-by: Ahmed Salem <x0rw3ll@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/12685690.O9o76ZdvQC@rjwysocki.net