mfd: atmel-smc: Ensure match is initialised

If the test in the for loop is never matched then the variable 'match'
will never be assigned to. Provide an initial value so this cannot be a
problem.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody@linaro.org>

drivers/mfd/atmel-smc.c

@@ -347,7 +347,7 @@ const struct atmel_hsmc_reg_layout *
 atmel_hsmc_get_reg_layout(ofnode np)
 {
 	int i;
-	const struct udevice_id *match;
+	const struct udevice_id *match = NULL;
 	const char *name;
 	int len;