openvswitch: Allocate struct ovs_pcpu_storage dynamically

PERCPU_MODULE_RESERVE defines the maximum size that can by used for the
per-CPU data size used by modules. This is 8KiB.

Commit 035fcdc4 ("openvswitch: Merge three per-CPU structures into
one") restructured the per-CPU memory allocation for the module and
moved the separate alloc_percpu() invocations at module init time to a
static per-CPU variable which is allocated by the module loader.

The size of the per-CPU data section for openvswitch is 6488 bytes which
is ~80% of the available per-CPU memory. Together with a few other
modules it is easy to exhaust the available 8KiB of memory.

Allocate ovs_pcpu_storage dynamically at module init time.

Reported-by: Gal Pressman <gal@nvidia.com>
Closes: https://lore.kernel.org/all/c401e017-f8db-4f57-a1cd-89beb979a277@nvidia.com


Fixes: 035fcdc4 ("openvswitch: Merge three per-CPU structures into one")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20250613123629.-XSoQTCu@linutronix.de


Signed-off-by: Paolo Abeni <pabeni@redhat.com>