net/mlx4_core: Read HCA frequency and map internal clock

Read HCA frequency, read PCI clock bar and offset, map internal clock to
PCI bar.

Signed-off-by: Eugenia Emantayev <eugenia@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>