Always use clrex for post-ARMv6 architectures

On ARMv6, clrex is supported only on the K extension but it is always
available starting with ARMv7.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm/kernel/entry-armv.S

@@ -566,7 +566,7 @@ ENTRY(__switch_to)
 	ldr	r6, [r2, #TI_CPU_DOMAIN]!
 #endif
 #if __LINUX_ARM_ARCH__ >= 6
-#ifdef CONFIG_CPU_32v6K
+#if defined(CONFIG_CPU_32v6K) || __LINUX_ARM_ARCH__ > 6
 	clrex
 #else
 	strex	r5, r4, [ip]			@ Clear exclusive monitor