platform-intel: fix buffer overflow

platform-intel: fix buffer overflow

mdadm -C /dev/md/imsm0 -e imsm -n 2 /dev/nvme5n1 /dev/nvme4n1 -R
mdadm -C /dev/md/r0d2 -l 0 -n 2 /dev/nvme5n1 /dev/nvme4n1 -R
*** buffer overflow detected ***: terminated
Aborted (core dumped)

Issue is related to D_FORTIFY_SOURCE=3 flag and depends on environment,
especially compiler version. In function active_arrays_by_format length of
path buffer is calculated dynamically based on parameters, while PATH_MAX
is used in snprintf, this is my lead to buffer overflow.

It is fixed by change dynamic length calculation, to use define PATH_MAX
for path length.

Signed-off-by: Blazej Kucman <blazej.kucman@intel.com>