Define IH_CPU_AVR32

Make it possible to generate AVR32 uImage files with mkimage and
make cmd_bootm recognize them.
Patch by Haavard Skinnemoen, 22 Sep 2006

tools/mkimage.c

@@ -94,6 +94,7 @@ table_entry_t arch_name[] = {
     {	IH_CPU_SPARC,		"sparc",	"SPARC",	},
     {	IH_CPU_SPARC64,		"sparc64",	"SPARC 64 Bit",	},
     {	IH_CPU_BLACKFIN,	"blackfin",	"Blackfin",	},
+    {	IH_CPU_AVR32,		"avr32",	"AVR32",	},
     {	-1,			"",		"",		},
 };