IB/mlx4: Replace kfree with kvfree in mlx4_ib_destroy_srq

IB/mlx4: Replace kfree with kvfree in mlx4_ib_destroy_srq

Upstream commit 0ef2f05c7e02ff99c0b5b583d7dee2cd12b053f2 uses vmalloc for
WR buffers when needed and uses kvfree to free the buffers. It missed
changing kfree to kvfree in mlx4_ib_destroy_srq().

Reported-by: Matthew Finaly <matt@Mellanox.com>
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Backport from upstream: df4176677fdf7ac0c5748083eb7a5b269fb1e156

Orabug: 22487409
Reviewed-by:  Wengang Wang <wen.gang.wang@oracle.com>
Acked-by: Ajaykumar Hotchandani <ajaykumar.hotchandani@oracle.com>
Acked-by: Yuval Shaia <yuval.shaia@oracle.com>