sparc64: Abstract away the %pcr values used to enable/disable NMI

We assumed PCR_PIC_PRIV can always be used to disable it, but that
won't be true for SPARC-T4.

This allows us also to get rid of some messy defines used in only
one location.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/pcr.h b/arch/sparc/include/asm/pcr.h
index 4c71bec..9ebc7f3 100644
--- a/arch/sparc/include/asm/pcr.h
+++ b/arch/sparc/include/asm/pcr.h
@@ -7,6 +7,8 @@
 	u64 (*read_pic)(unsigned long);
 	void (*write_pic)(unsigned long, u64);
 	u64 (*nmi_picl_value)(unsigned int nmi_hz);
+	u64 pcr_nmi_enable;
+	u64 pcr_nmi_disable;
 };
 extern const struct pcr_ops *pcr_ops;
 
@@ -30,8 +32,6 @@
 #define PCR_N2_SL1_SHIFT	27
 #define PCR_N2_OV1		0x80000000
 
-extern u64 pcr_enable;
-
 extern int pcr_arch_init(void);
 
 #endif /* __PCR_H */