Staging: sbe-2t3e3: Fix smatch warning of function definition with external linkage

This patch fixes the following smatch warning in cpld.c-
drivers/staging/sbe-2t3e3/cpld.c:243:13: warning: function 'cpld_set_clock' with external linkage has definition
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/sbe-2t3e3/cpld.c

@@ -240,7 +240,7 @@ void cpld_select_panel(struct channel *sc, u32 panel)
 }
 
 
-extern void cpld_set_clock(struct channel *sc, u32 mode)
+void cpld_set_clock(struct channel *sc, u32 mode)
 {
 	if (sc->p.clock_source == mode)
 		return;