MIPS: Add definitions of SegCtl registers and use them

The SegCtl registers are standard for MIPSr3..MIPSr5. Add definitions of
these registers and use them rather than constants

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: Joshua Kinard <kumba@gentoo.org>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Chris Packham <judge.packham@gmail.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13290/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 25d0157..8471905 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -48,6 +48,9 @@
 #define CP0_CONF $3
 #define CP0_CONTEXT $4
 #define CP0_PAGEMASK $5
+#define CP0_SEGCTL0 $5, 2
+#define CP0_SEGCTL1 $5, 3
+#define CP0_SEGCTL2 $5, 4
 #define CP0_WIRED $6
 #define CP0_INFO $7
 #define CP0_HWRENA $7, 0