staging: lustre: service.c: make local functions static

Makes functions that are not used outside the file in which they are defined
static, as reported by sparse:

drivers/staging/lustre/lustre/ptlrpc/service.c:72:35: warning: symbol
'ptlrpc_alloc_rqbd' was not declared. Should it be static?
1065 drivers/staging/lustre/lustre/ptlrpc/service.c:105:1: warning:
symbol 'ptlrpc_free_rqbd' was not declared. Should it be static?
1066 drivers/staging/lustre/lustre/ptlrpc/service.c:122:1: warning:
symbol 'ptlrpc_grow_req_bufs' was not declared. Should it be static?
1067 drivers/staging/lustre/lustre/ptlrpc/service.c:3055:5: warning:
symbol 'ptlrpc_svcpt_health_check' was not declared. Should it be
static?

Signed-off-by: Zoltán Lajos Kis <zoltan.lajos.kis@gmail.com&gt;">
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>