[PATCH -next] arm64: mm: Fix unused variable warning in zone_sizes_init

[Nathan Chancellor]

When building arm64 allnoconfig, CONFIG_ZONE_DMA and CONFIG_ZONE_DMA32
get disabled so there is a warning about max_dma being unused.

../arch/arm64/mm/init.c:215:16: warning: unused variable 'max_dma'
[-Wunused-variable]
        unsigned long max_dma = min;
                      ^
1 warning generated.

Add an ifdef around the variable to fix this.

Fixes: 1a8e1cef7603 ("arm64: use both ZONE_DMA and ZONE_DMA32")
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---
 arch/arm64/mm/init.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 44f07fdf7a59..c3d6657b9942 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -212,7 +212,9 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max)
 	struct memblock_region *reg;
 	unsigned long zone_size[MAX_NR_ZONES], zhole_size[MAX_NR_ZONES];
 	unsigned long max_dma32 = min;
+#if defined(CONFIG_ZONE_DMA) || defined(CONFIG_ZONE_DMA)
 	unsigned long max_dma = min;
+#endif
 
 	memset(zone_size, 0, sizeof(zone_size));
 
-- 
2.23.0