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>
(cherry picked from commit 5ec9d756aac1a0eb5c1f48eb110e80946b43f41a)
dahdi: Fix previous CentOS 6.5 commit.

The previous commit from earlier today to fix the backport of PDE_DATA was
wrong in that it would not then process the other defines for older kernels if
it detected it was running on a redhat release.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>
(cherry picked from commit 71c003ba49a348ed322ee100ca5a058fd0bfab2d)