misc: sgi-xp: xp_main: make some symbols static

The sparse tool complains as follows:

drivers/misc/sgi-xp/xp_main.c:24:22: warning:
 symbol 'xp_dbg_name' was not declared. Should it be static?
drivers/misc/sgi-xp/xp_main.c:28:15: warning:
 symbol 'xp_dbg_subname' was not declared. Should it be static?

These symbols are not used outside of xp_main.c, so this
commit marks them static.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Link: https://lore.kernel.org/r/20210324084823.7393-1-zou_wei@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/sgi-xp/xp_main.c

@@ -21,11 +21,11 @@
 
 /* define the XP debug device structures to be used with dev_dbg() et al */
 
-struct device_driver xp_dbg_name = {
+static struct device_driver xp_dbg_name = {
 	.name = "xp"
 };
 
-struct device xp_dbg_subname = {
+static struct device xp_dbg_subname = {
 	.init_name = "",		/* set to "" */
 	.driver = &xp_dbg_name
 };