linuxkpi: Move timer related functions in its own file.

[manu]

Summary

While here prefix the functions with lkpi_

No functional changes intended.

[emaste]

sys/compat/linuxkpi/common/src/linux_timer.c

3–5

It looks like the routines moved to this file are all from Mellanox changes in 2015 and on.
git diff 58cb7b5be4f9ad0244294ede8f942bb76b37ca6f:sys/ofed/include/linux/linux_compat.c HEAD:sys/compat/linuxkpi/common/src/linux_compat.c

[manu]

sys/compat/linuxkpi/common/src/linux_timer.c

3–5

I'll admit that I've not looked in the history to find who it belong too.
I'll update the licence accordingly (and also add the new files to sys/conf/files).

[bz]

I haven't tried it but scrolling through it looks ok to me.

sys/compat/linuxkpi/common/src/linux_timer.c

50

does this actually belong into linux/gcd.h these days? (not sure if it is a public function or not possibly needed for anything else).
Maybe longer-term.

[manu]

sys/compat/linuxkpi/common/src/linux_timer.c

50

gcd.h only have unsigned long gcd(unsigned long a, unsigned long b) attribute_const;
This one is only used locally as we nned 64bits int for time calculation.