parisc: Add constants for control registers and clean up mfctl()

Clean up the code for the mfctl() and mtctl() functions and add often
used constants.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/include/asm/special_insns.h

@@ -30,11 +30,15 @@
 	pa;						\
 })
 
+#define CR_EIEM 15	/* External Interrupt Enable Mask */
+#define CR_CR16 16	/* CR16 Interval Timer */
+#define CR_EIRR 23	/* External Interrupt Request Register */
+
 #define mfctl(reg)	({		\
 	unsigned long cr;		\
 	__asm__ __volatile__(		\
-		"mfctl " #reg ",%0" :	\
-		 "=r" (cr)		\
+		"mfctl %1,%0" :		\
+		 "=r" (cr) : "i" (reg)	\
 	);				\
 	cr;				\
 })
@@ -44,13 +48,8 @@
 		: /* no outputs */ \
 		: "r" (gr), "i" (cr) : "memory")
 
-/* these are here to de-mystefy the calling code, and to provide hooks */
-/* which I needed for debugging EIEM problems -PB */
-#define get_eiem() mfctl(15)
-static inline void set_eiem(unsigned long val)
-{
-	mtctl(val, 15);
-}
+#define get_eiem()	mfctl(CR_EIEM)
+#define set_eiem(val)	mtctl(val, CR_EIEM)
 
 #define mfsp(reg)	({		\
 	unsigned long cr;		\