[ARM] Fix ARM build (, -> _)

The kbuild infrastructure in 2.5.21 uses the filename to generate a
dependency file, which is passed into gcc using -Wp,-MD,filename.
Unfortunately, the ',' in the filename is interpreted by GCC as an
argument separator for the preprocessor.  So, with a filename
foo,bar.c gcc ends up passing the three arguments "-MD", "foo" and
"bar.c" to cpp, which promptly complains.

We therefore rename these files to use an underscore instead of a
comma.

arch/arm/mm/Makefile

@@ -26,11 +26,11 @@ obj-$(CONFIG_ALIGNMENT_TRAP) += alignment.o
 obj-$(CONFIG_DISCONTIGMEM) += discontig.o
 
 # Select the processor-specific files
-p-$(CONFIG_CPU_26)	+= proc-arm2,3.o
+p-$(CONFIG_CPU_26)	+= proc-arm2_3.o
 
 # ARMv3
-p-$(CONFIG_CPU_ARM610)	+= proc-arm6,7.o  tlb-v3.o   copypage-v3.o
-p-$(CONFIG_CPU_ARM710)	+= proc-arm6,7.o  tlb-v3.o   copypage-v3.o
+p-$(CONFIG_CPU_ARM610)	+= proc-arm6_7.o  tlb-v3.o   copypage-v3.o
+p-$(CONFIG_CPU_ARM710)	+= proc-arm6_7.o  tlb-v3.o   copypage-v3.o
 
 # ARMv4
 p-$(CONFIG_CPU_ARM720T)	+= proc-arm720.o  tlb-v4.o   copypage-v4wt.o abort-lv4t.o