RDMA/IPoIB: Limit the ipoib_dev_uninit_default scope

RDMA/IPoIB: Limit the ipoib_dev_uninit_default scope

ipoib_dev_uninit_default() call is used in ipoib_main.c file only
and it generates the following warning from smatch tool:
	drivers/infiniband/ulp/ipoib/ipoib_main.c:1593:6: warning:
	symbol 'ipoib_dev_uninit_default' was not declared. Should it
	be static?

so let's declare that function as static.

Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>