Staging: lustre: Mark internal functions static in llog_cat.c

This patch marks functions llog_cat_set_first_idx and cat_cancel_cb
static as these are used only within this file. Also since cat_cancel_cb
is made static do not export it.

This eliminates the following sparse warning:
warning: symbol * was not declared. Should it be static?

Signed-off-by: Darshana Padmadas <darshanapadmadas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>