x86: bios_uv.c: uv_systab should be static

Impact: cleanup, reduce kernel size a bit, avoid sparse warning

Fixes sparse warning:
arch/x86/kernel/bios_uv.c:28:18: warning: symbol 'uv_systab' was not declared. Should it be static?
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/kernel/bios_uv.c

@@ -25,7 +25,7 @@
 #include <asm/uv/bios.h>
 #include <asm/uv/uv_hub.h>
 
-struct uv_systab uv_systab;
+static struct uv_systab uv_systab;
 
 s64 uv_bios_call(enum uv_bios_cmd which, u64 a1, u64 a2, u64 a3, u64 a4, u64 a5)
 {