[ARM] pxa: silence warnings from cpu_is_xxx() macros

If only a single CPU type is selected, __cpu_is_xxx() doesn't
use its argument.  This causes the compiler to issue a warning
about an unused variable in the parent function.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/include/asm-arm/system.h b/include/asm-arm/system.h
index 94ea8c6..28425c4 100644
--- a/include/asm-arm/system.h
+++ b/include/asm-arm/system.h
@@ -75,8 +75,21 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/linkage.h>
+#include <linux/stringify.h>
 #include <linux/irqflags.h>
 
+/*
+ * The CPU ID never changes at run time, so we might as well tell the
+ * compiler that it's constant.  Use this function to read the CPU ID
+ * rather than directly reading processor_id or read_cpuid() directly.
+ */
+static inline unsigned int read_cpuid_id(void) __attribute_const__;
+
+static inline unsigned int read_cpuid_id(void)
+{
+	return read_cpuid(CPUID_ID);
+}
+
 #define __exception	__attribute__((section(".exception.text")))
 
 struct thread_info;