x86: Disable EXECMEM_ROX support

The whole module_writable_address() nonsense made a giant mess of
alternative.c, not to mention it still contains bugs -- notable some of the
CFI variants crash and burn.

Mike has been working on patches to clean all this up again, but given the
current state of things, this stuff just isn't ready.

Disable for now, lets try again next cycle.

Fixes: 5185e7f ("x86/module: enable ROX caches for module text on 64 bit")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250113112934.GA8385@noisy.programming.kicks-ass.net

Author: Peter Zijlstra

arch/x86/Kconfig

@@ -83,7 +83,6 @@ config X86
 	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
 	select ARCH_HAS_EARLY_DEBUG		if KGDB
 	select ARCH_HAS_ELF_RANDOMIZE
-	select ARCH_HAS_EXECMEM_ROX		if X86_64
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL