staging: lustre: clean function declarations in class_obd.c up

staging: lustre: clean function declarations in class_obd.c up

We get 2 warnings when building kernel with W=1:

drivers/staging/lustre/lustre/obdclass/linux/linux-module.c:413:5: warning: no previous prototype for 'class_procfs_init' [-Wmissing-prototypes]
drivers/staging/lustre/lustre/obdclass/linux/linux-module.c:449:5: warning: no previous prototype for 'class_procfs_clean' [-Wmissing-prototypes]

In fact, both functions are declared in
drivers/staging/lustre/lustre/obdclass/class_obd.c,but should be
declared in a header file, thus can be recognized in other file.

So this patch moves the declarations into
drivers/staging/lustre/lustre/include/obd_class.h.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>