misc: sgi-xp: xp_main: Staticify local functions xp_init() and xp_exit()

These functions are not exported and no external prototypes exist

Fixes W=1 kernel build warning(s):

 drivers/misc/sgi-xp/xp_main.c:227:1: warning: no previous prototype for ‘xp_init’ [-Wmissing-prototypes]
 227 | xp_init(void)
 | ^~~~~~~
 drivers/misc/sgi-xp/xp_main.c:250:1: warning: no previous prototype for ‘xp_exit’ [-Wmissing-prototypes]
 250 | xp_exit(void)
 | ^~~~~~~

Cc: Cliff Whickman <cpw@sgi.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Dean Nelson <dcn@sgi.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200701083118.45744-5-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/sgi-xp/xp_main.c

@@ -223,7 +223,7 @@ xpc_disconnect(int ch_number)
 }
 EXPORT_SYMBOL_GPL(xpc_disconnect);
 
-int __init
+static int __init
 xp_init(void)
 {
 	enum xp_retval ret;
@@ -246,7 +246,7 @@ xp_init(void)
 
 module_init(xp_init);
 
-void __exit
+static void __exit
 xp_exit(void)
 {
 	if (is_uv())