fbdev: via/via_clock: fix sparse warning

this patch fixes following sparse warning:

via_clock.c:33:12: warning: symbol 'via_slap' was not declared. Should it be static?
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/via/via_clock.c

@@ -30,7 +30,7 @@
 #include "global.h"
 #include "debug.h"
 
-const char *via_slap = "Please slap VIA Technologies to motivate them "
+static const char *via_slap = "Please slap VIA Technologies to motivate them "
 	"releasing full documentation for your platform!\n";
 
 static inline u32 cle266_encode_pll(struct via_pll_config pll)