[MIPS] Define MIPS_CPU_IRQ_BASE in generic header

The irq_base for {mips,rm7k,rm9k}_cpu_irq_init() are constant on all
platforms and are same value on most platforms (0 or 16, depends on
CONFIG_I8259).  Define them in asm-mips/mach-generic/irq.h and make
them customizable.  This will save a few cycle on each CPU interrupt.

A good side effect is removing some dependencies to MALTA in generic
SMTC code.

Although MIPS_CPU_IRQ_BASE is customizable, this patch changes irq
mappings on DDB5477, EMMA2RH and MIPS_SIM, since really customizing
them might cause some header dependency problem and there seems no
good reason to customize it.  So currently only VR41XX is using custom
MIPS_CPU_IRQ_BASE value, which is 0 regardless of CONFIG_I8259.

Testing this patch on those platforms is greatly appreciated.  Thank
you.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

include/asm-mips/mips-boards/atlasint.h

@@ -26,10 +26,12 @@
 #ifndef _MIPS_ATLASINT_H
 #define _MIPS_ATLASINT_H
 
+#include <irq.h>
+
 /*
  * Interrupts 0..7 are used for Atlas CPU interrupts (nonEIC mode)
  */
-#define MIPSCPU_INT_BASE	0
+#define MIPSCPU_INT_BASE	MIPS_CPU_IRQ_BASE
 
 /* CPU interrupt offsets */
 #define MIPSCPU_INT_SW0		0

include/asm-mips/mips-boards/maltaint.h

@@ -25,6 +25,8 @@
 #ifndef _MIPS_MALTAINT_H
 #define _MIPS_MALTAINT_H
 
+#include <irq.h>
+
 /*
  * Interrupts 0..15 are used for Malta ISA compatible interrupts
  */
@@ -33,7 +35,7 @@
 /*
  * Interrupts 16..23 are used for Malta CPU interrupts (nonEIC mode)
  */
-#define MIPSCPU_INT_BASE	16
+#define MIPSCPU_INT_BASE	MIPS_CPU_IRQ_BASE
 
 /* CPU interrupt offsets */
 #define MIPSCPU_INT_SW0		0

include/asm-mips/mips-boards/seadint.h

@@ -20,10 +20,12 @@
 #ifndef _MIPS_SEADINT_H
 #define _MIPS_SEADINT_H
 
+#include <irq.h>
+
 /*
  * Interrupts 0..7 are used for SEAD CPU interrupts
  */
-#define MIPSCPU_INT_BASE	0
+#define MIPSCPU_INT_BASE	MIPS_CPU_IRQ_BASE
 
 #define MIPSCPU_INT_UART0	2
 #define MIPSCPU_INT_UART1	3

include/asm-mips/mips-boards/simint.h

@@ -17,10 +17,11 @@
 #ifndef _MIPS_SIMINT_H
 #define _MIPS_SIMINT_H
 
+#include <irq.h>
 
 #define SIM_INT_BASE		0
 #define MIPSCPU_INT_MB0		2
-#define MIPSCPU_INT_BASE	16
+#define MIPSCPU_INT_BASE	MIPS_CPU_IRQ_BASE
 #define MIPS_CPU_TIMER_IRQ	7