m68knommu: Replace deprecated strcpy with strscpy in init_ucsimm

strcpy() has been deprecated [1] because it performs no bounds checking
on the destination buffer, which can lead to buffer overflows. Replace
it with the safer strscpy().

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1]
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Greg Ungerer <gerg@kernel.org>