dcb: Fix compilation warning about reallocarray

dcb: Fix compilation warning about reallocarray

In older distros we need bsd/stdlib.h but newer distro doesn't
need it. Also old distro will need libbsd-devel installed and newer
doesn't. To remove a possible dependency on libbsd-devel replace usage
of reallocarray to realloc.

dcb_app.c: In function ‘dcb_app_table_push’:
dcb_app.c:68:25: warning: implicit declaration of function ‘reallocarray’; did you mean ‘realloc’?

Fixes: 8e9bed1493f5 ("dcb: Add a subtool for the DCB APP object")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>