ARM: Do not enable SWP emulation if CPU_V6 && CPU_V7

This option uses LDREXB/STREXB to emulate SWPB but these instructions
are not supported on all the ARMv6 processors.
Reported-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Leif Lindholm <Leif.Lindholm@arm.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mm/Kconfig

@@ -644,7 +644,7 @@ config ARM_THUMBEE
 
 config SWP_EMULATE
 	bool "Emulate SWP/SWPB instructions"
-	depends on CPU_V7
+	depends on CPU_V7 && !CPU_V6
 	select HAVE_PROC_CPU if PROC_FS
 	default y if SMP
 	help