arch/parisc/kernel/perf_asm.S: build fix

Missing <linux/init.h> header for __HEAD macro.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/kernel/perf_asm.S

@@ -20,6 +20,8 @@
  */
 
 #include <asm/assembly.h>
+
+#include <linux/init.h>
 #include <linux/linkage.h>
 
 #ifdef CONFIG_64BIT