x86/cpu: Drop unused Kconfig symbol X86_P6_NOP

This symbol was removed in early 2025 but 2 dangling references to it
were missed. Delete them now.

It should be safe to drop the -mtune=generic32 option since gcc 4.3
and later do not cause the problem (see 28f7e66 ("x86: prevent
binutils from being "smart" and generating NOPLs for us")). Also, Arnd
confirmed this with gcc-8 and gcc-15 (see Link:).

Fixes: f388f60 ("x86/cpu: Drop configuration options for early 64-bit CPUs")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://patch.msgid.link/20260106014708.991447-1-rdunlap@infradead.org
Link: https://lore.kernel.org/all/c0f0814a-8333-49e1-8e50-740e4c88d94b@app.fastmail.com/

Author: rddunlap

arch/x86/Kconfig.cpufeatures

@@ -38,7 +38,7 @@ config X86_REQUIRED_FEATURE_ALWAYS
 
 config X86_REQUIRED_FEATURE_NOPL
 	def_bool y
-	depends on X86_64 || X86_P6_NOP
+	depends on X86_64
 
 config X86_REQUIRED_FEATURE_CX8
 	def_bool y

arch/x86/Makefile_32.cpu

@@ -42,9 +42,3 @@ cflags-$(CONFIG_MGEODE_LX)	+= $(call cc-option,-march=geode,-march=pentium-mmx)
 # add at the end to overwrite eventual tuning options from earlier
 # cpu entries
 cflags-$(CONFIG_X86_GENERIC) 	+= $(call tune,generic,$(call tune,i686))
-
-# Bug fix for binutils: this option is required in order to keep
-# binutils from generating NOPL instructions against our will.
-ifneq ($(CONFIG_X86_P6_NOP),y)
-cflags-y			+= $(call cc-option,-Wa$(comma)-mtune=generic32,)
-endif