Revert "scripts/gdb: bail early if there are no generic PD"

This reverts commit 30ac77e9.

It breaks the Android kernel abi, so revert it.  If it needs to come
back later, it can do so in an abi-safe way.

Bug: 161946584
Change-Id: I0a365fa1214679c573c09af4df2d85f1a7c9640d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>