dahdi: CentOS 6.5 backported PDE_DATA definition.

This will fix the "error: redefinition of 'PDE_DATA'" error when compiling.

Internal-Issue-ID: DAHLIN-330
Signed-off-by: Shaun Ruffell <sruffell@digium.com>
wcxb: is_pcie -> pci_is_pcie()

is_pcie attribute was finally dropped from struct pci_dev in
upstream commit 115e3bc5e23e7ec3c85a2014bfa96c0ddd036083.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>