sgi-xp: make some symbols static in xpc_main.c

sgi-xp: make some symbols static in xpc_main.c

Fix the following sparse warning:

drivers/misc/sgi-xp/xpc_main.c:62:22: warning: symbol 'xpc_dbg_name' was
not declared. Should it be static?
drivers/misc/sgi-xp/xpc_main.c:66:15: warning: symbol
'xpc_part_dbg_subname' was not declared. Should it be static?
drivers/misc/sgi-xp/xpc_main.c:71:15: warning: symbol
'xpc_chan_dbg_subname' was not declared. Should it be static?
drivers/misc/sgi-xp/xpc_main.c:1221:1: warning: symbol 'xpc_init' was
not declared. Should it be static?
drivers/misc/sgi-xp/xpc_main.c:1323:1: warning: symbol 'xpc_exit' was
not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200410063618.27143-2-yanaijie@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>