linuxkpi: Add macros for might_lock_nested() and lockdep_(re/un/)pin_lock()

In Linux, these are macros to locks in the kernel for scheduling purposes.
But as with other macros in this header, we aren't doing anything with them
so we are doing do {} while (0) for now.

This is needed by the drm-kmod 5.7 update.

Approved by: hselasky (src)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D30710