MIPS: r4k-bugs64: Limit R4k bug checks to affected systems

Only build the checks for R4k errata workarounds if we expect that the
kernel might actually run on a system with an R4k CPU - ie.
CONFIG_SYS_HAS_CPU_R4X00=y & we're targeting a pre-MIPSr1 ISA revision.

Rename cpu-bugs64.c to r4k-bugs64.c to indicate the fact that the code
is specific to R4k CPUs.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org

arch/mips/kernel/Makefile

@@ -80,7 +80,7 @@ obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_PROC_FS)		+= proc.o
 obj-$(CONFIG_MAGIC_SYSRQ)	+= sysrq.o
 
-obj-$(CONFIG_64BIT)		+= cpu-bugs64.o
+obj-$(CONFIG_CPU_R4X00_BUGS64)	+= r4k-bugs64.o
 
 obj-$(CONFIG_I8253)		+= i8253.o
 

arch/mips/kernel/genex.S

@@ -657,7 +657,7 @@ isrdhwr:
 	.set	pop
 	END(handle_ri_rdhwr)
 
-#ifdef CONFIG_64BIT
+#ifdef CONFIG_CPU_R4X00_BUGS64
 /* A temporary overflow handler used by check_daddi(). */
 
 	__INIT