staging/lustre: remove wrappers for timer functions

This is a simple cleanup that I did after noticing that the abstraction
for the timer functions in completely pointless, and the one user (ptlrpc)
can just as well call the native Linux functions.

For good measure, this also removes the empty libcfs_arch_init()
and libcfs_arch_cleanup() functions that are defined in the
same file.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>