ALSA: sound/mixart: avoid redefining {readl,write}_{le,be} accessors

If the platform already provides a definition for these accessors
do not redefine them. The warning was caught on MIPS.
Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/mixart/mixart_hwdep.h

@@ -25,11 +25,21 @@
 
 #include <sound/hwdep.h>
 
+#ifndef readl_be
 #define readl_be(x) be32_to_cpu(__raw_readl(x))
+#endif
+
+#ifndef writel_be
 #define writel_be(data,addr) __raw_writel(cpu_to_be32(data),addr)
+#endif
 
+#ifndef readl_le
 #define readl_le(x) le32_to_cpu(__raw_readl(x))
+#endif
+
+#ifndef writel_le
 #define writel_le(data,addr) __raw_writel(cpu_to_le32(data),addr)
+#endif
 
 #define MIXART_MEM(mgr,x)	((mgr)->mem[0].virt + (x))
 #define MIXART_REG(mgr,x)	((mgr)->mem[1].virt + (x))