memblock test: fix implicit declaration of function 'strscpy'

Commit 1e4c64b7 ("mm/memblock: Add "reserve_mem" to reserved named
memory at boot up") introduce the usage of strscpy, which breaks the
memblock test.

Let's define it as strcpy in userspace to fix it.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Link: https://lore.kernel.org/r/20240806010319.29194-5-richard.weiyang@gmail.com


Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>