ARM: imx: call imx6sx_cpuidle_init() conditionally for 6sll

The imx6sl platform has two different cpuidle implementations,
and fails to link if we only want one of the two:

arch/arm/mach-imx/mach-imx6sl.o: In function `imx6sl_init_late':
mach-imx6sl.c:(.init.text+0x12): undefined reference to `imx6sx_cpuidle_init'

This makes the call into reference conditional on the configuration.

Fixes: e7fa1fb39b ("ARM: imx: add cpu idle support for i.MX6SLL")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/mach-imx/mach-imx6sl.c

@@ -42,9 +42,9 @@ static void __init imx6sl_init_late(void)
 	if (IS_ENABLED(CONFIG_ARM_IMX6Q_CPUFREQ))
 		platform_device_register_simple("imx6q-cpufreq", -1, NULL, 0);
 
-	if (cpu_is_imx6sl())
+	if (IS_ENABLED(CONFIG_SOC_IMX6SL) && cpu_is_imx6sl())
 		imx6sl_cpuidle_init();
-	else
+	else if (IS_ENABLED(CONFIG_SOC_IMX6SLL))
 		imx6sx_cpuidle_init();
 }