x86/Kconfig: Correct reference to MWINCHIP3D

Commit in Fixes intended to exclude the Winchip series and referred to
CONFIG_WINCHIP3D, but the config symbol is called CONFIG_MWINCHIP3D.

Hence, scripts/checkkconfigsymbols.py warns:

WINCHIP3D
Referencing files: arch/x86/Kconfig

Correct the reference to the intended config symbol.

Fixes: 69b8d3fcab ("x86/Kconfig: Exclude i586-class CPUs lacking PAE support from the HIGHMEM64G Kconfig group")
Suggested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20210803113531.30720-4-lukas.bulwahn@gmail.com

arch/x86/Kconfig

@@ -1405,7 +1405,7 @@ config HIGHMEM4G
 
 config HIGHMEM64G
 	bool "64GB"
-	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6
+	depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !MWINCHIP3D && !MK6
 	select X86_PAE
 	help
 	  Select this if you have a 32-bit processor and more than 4