Introduce arch_atomic64_try_cmpxchg() for 32-bit targets to use
optimized target specific implementation instead of a generic one.
This implementation eliminates dual-word compare after
cmpxchg8b instruction and improves generated asm code from:

    2273:	f0 0f c7 0f          	lock cmpxchg8b (%edi)
    2277:	8b 74 24 2c          	mov    0x2c(%esp),%esi
    227b:	89 d3                	mov    %edx,%ebx
    227d:	89 c2                	mov    %eax,%edx
    227f:	89 5c 24 10          	mov    %ebx,0x10(%esp)
    2283:	8b 7c 24 30          	mov    0x30(%esp),%edi
    2287:	89 44 24 1c          	mov    %eax,0x1c(%esp)
    228b:	31 f2                	xor    %esi,%edx
    228d:	89 d0                	mov    %edx,%eax
    228f:	89 da                	mov    %ebx,%edx
    2291:	31 fa                	xor    %edi,%edx
    2293:	09 d0                	or     %edx,%eax
    2295:	0f 85 a5 00 00 00    	jne    2340 <...>

to:

    2270:	f0 0f c7 0f          	lock cmpxchg8b (%edi)
    2274:	0f 85 a6 00 00 00    	jne    2320 <...>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240410062957.322614-1-ubizjak@gmail.com