linuxkpi: Define PCI_IRQ_LEGACY for Linux < 6.10
Commit 03e39d3d42e70482cd6f65ecaa5cf8ff9674d27c decreased the Linux
version that exposes this constant to be Linux 6.7. It happens that the
constant is older.
However, it is removed in Linux 6.10. Let's change the version condition
to say that it is defined for any version before 6.10.
Reported by: bz
Reviewed by: bz
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D48861