powerpc/5200: Build fix for mpc52xx watchdog timer code

mpc52xx_gpt_wdt_setup is defined as 0, which causes the following build
failure with gcc 4.5, since it's built with -Werror.

arch/powerpc/platforms/52xx/mpc52xx_gpt.c:761:3: error: statement with no effect

Changing it to a static inline fixes the problem.

Reported-by: Jeff Mahoney <[e-mail]>
Signed-off-by: Grant Likely <[e-mail]>

arch/powerpc/platforms/52xx/mpc52xx_gpt.c

···
 	return 0;
 }
 
-#define mpc52xx_gpt_wdt_setup(x, y)		(0)
+static inline int mpc52xx_gpt_wdt_setup(struct mpc52xx_gpt_priv *gpt,
+					const u32 *period)
+{
+	return 0;
+}
 
 #endif	/*  CONFIG_MPC5200_WDT	*/