avr32: Retire AVR32 for good

AVR32 is gone. It's already more than two years for no support in Buildroot,
even longer there is no support in GCC (last version is heavily patched 4.2.4).

Linux kernel v4.12 got rid of it (and v4.11 didn't build successfully).

There is no good point to keep this support in U-Boot either.

Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

README

@@ -136,7 +136,6 @@ Directory Hierarchy:
 /arch			Architecture specific files
   /arc			Files generic to ARC architecture
   /arm			Files generic to ARM architecture
-  /avr32		Files generic to AVR32 architecture
   /m68k			Files generic to m68k architecture
   /microblaze		Files generic to microblaze architecture
   /mips			Files generic to MIPS architecture
@@ -320,9 +319,6 @@ The following options need to be configured:
 
 - Board Type:	Define exactly one, e.g. CONFIG_MPC8540ADS.
 
-- CPU Daughterboard Type: (if CONFIG_ATSTK1000 is defined)
-		Define exactly one, e.g. CONFIG_ATSTK1002
-
 - Marvell Family Member
 		CONFIG_SYS_MVFS		- define it if you want to enable
 					  multiple fs option at one time
@@ -4810,9 +4806,9 @@ details; basically, the header defines the following image properties:
   LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
   Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
   INTEGRITY).
-* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
+* Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
   IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
-  Currently supported: ARM, AVR32, Intel x86, MIPS, NDS32, Nios II, PowerPC).
+  Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
 * Compression Type (uncompressed, gzip, bzip2)
 * Load Address
 * Entry Point