ARM: mvebu: build armada375-smp code conditionally

mvebu_armada375_smp_wa_init is only used on armada 375 but is defined
for all mvebu machines. As it calls a function that is only provided
sometimes, this can result in a link error:

arch/arm/mach-mvebu/built-in.o: In function `mvebu_armada375_smp_wa_init':
:(.text+0x228): undefined reference to `mvebu_setup_boot_addr_wa'

To solve this, we can just change the existing #ifdef around the
function to also check for Armada375 SMP platforms.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 305969f ("ARM: mvebu: use the common function for Armada 375 SMP workaround")
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Gregory Clement <gregory.clement@free-electrons.com>

arch/arm/mach-mvebu/system-controller.c

@@ -126,7 +126,7 @@ int mvebu_system_controller_get_soc_id(u32 *dev, u32 *rev)
 		return -ENODEV;
 }
 
-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) && defined(CONFIG_MACH_MVEBU_V7)
 void mvebu_armada375_smp_wa_init(void)
 {
 	u32 dev, rev;