Add cmpxchg_local to avr32

Add cmpxchg_local to avr32

Use the new generic cmpxchg_local (disables interrupt) for 8, 16 and 64 bits
cmpxchg_local. Use the __cmpxchg_u32 primitive for 32 bits cmpxchg_local.

Note that cmpxchg only uses the __cmpxchg_u32 or __cmpxchg_u64 and will cause
a linker error if called with 8 or 16 bits argument.

Signed-off-by: Mathieu Desnoyers <[email protected]>
Acked-by: Haavard Skinnemoen <[email protected]>
Cc: Haavard Skinnemoen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>