AVR32: Remove useless config option "GENERIC_BUST_SPINLOCK".

Remove the clearly useless config option GENERIC_BUST_SPINLOCK, which
is not used anywhere in the tree.
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

arch/avr32/Kconfig

@@ -57,9 +57,6 @@ config ARCH_HAS_ILOG2_U64
 	bool
 	default n
 
-config GENERIC_BUST_SPINLOCK
-	bool
-
 config GENERIC_HWEIGHT
 	bool
 	default y