Remove iwl_transport_register which was a W/A. The bus layer knows what
transport to use. So now, the bus layer gives the upper layer a pointer to the
iwl_trans_ops struct that it wants to use. The upper layer then, allocates the
desired transport layer using iwl_trans_ops->alloc function.

As a result of this, priv->trans, no longer exists, priv holds a pointer to
iwl_shared, which holds a pointer to iwl_trans. This required to change all the
calls to the transport layer from upper layer. While we were at it, trans_X
inlines have been renamed to iwl_trans_X to avoid confusions, which of course
required to rename the functions inside the transport layer because of
conflicts in names. So the static API functions inside the transport layer
implementation have been renamed to iwl_trans_pcie_X.

Until now, the IRQ / Tasklet were initialized in iwl_transport_layer. This is
confusing since the registration doesn't mean to request IRQ, so I added a
handler for that.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>