MIPS: Add P6600 PRID & cpu_type_enum values

Define the processor ID for the P6600 core and add a value to the enum
cpu_type_enum for the core.

[[e-mail]: Fix merge conflict.]

Signed-off-by: Paul Burton <[e-mail]>
Cc: Joshua Kinard <[e-mail]>
Cc: Leonid Yegoshin <[e-mail]>
Cc: James Hogan <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/12342/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/include/asm/cpu.h

···
 #define PRID_IMP_INTERAPTIV_MP	0xa100
 #define PRID_IMP_PROAPTIV_UP	0xa200
 #define PRID_IMP_PROAPTIV_MP	0xa300
+#define PRID_IMP_P6600		0xa400
 #define PRID_IMP_M5150		0xa700
 #define PRID_IMP_P5600		0xa800
 #define PRID_IMP_I6400		0xa900
···
 	CPU_ALCHEMY, CPU_PR4450, CPU_BMIPS32, CPU_BMIPS3300, CPU_BMIPS4350,
 	CPU_BMIPS4380, CPU_BMIPS5000, CPU_JZRISC, CPU_LOONGSON1, CPU_M14KC,
 	CPU_M14KEC, CPU_INTERAPTIV, CPU_P5600, CPU_PROAPTIV, CPU_1074K,
-	CPU_M5150, CPU_I6400,
+	CPU_M5150, CPU_I6400, CPU_P6600,
 
 	/*
 	 * MIPS64 class processors