x86/platform: Only allow CONFIG_EISA for 32-bit

The CONFIG_EISA menu was cleaned up in 2018, but this inadvertently
brought the option back on 64-bit machines: ISA remains guarded by
a CONFIG_X86_32 check, but EISA no longer depends on ISA.

The last Intel machines ith EISA support used a 82375EB PCI/EISA bridge
from 1993 that could be paired with the 440FX chipset on early Pentium-II
CPUs, long before the first x86-64 products.

Fixes: 6630a8e ("eisa: consolidate EISA Kconfig entry in drivers/eisa")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250226213714.4040853-11-arnd@kernel.org

arch/x86/Kconfig

@@ -233,7 +233,7 @@ config X86
 	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI	if X86_64
 	select HAVE_EBPF_JIT
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
-	select HAVE_EISA
+	select HAVE_EISA			if X86_32
 	select HAVE_EXIT_THREAD
 	select HAVE_GUP_FAST
 	select HAVE_FENTRY			if X86_64 || DYNAMIC_FTRACE