LinuxKPI: Add DEFINE_DEBUGFS_ATTRIBUTE_SIGNED to linux/debugfs.h
Sponsored by: Serenity CyberSecurity, LLC
MFC after: 1 week
Reviewed by: manu
Differential Revision: https://reviews.freebsd.org/D45615
(cherry picked from commit 8c5c572125665e3fd8a033d1a8b0a370e5a43e24)