[MIPS] Limit MIPS_MT to MIPS32R2 only.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3fa67af..b8616a0b 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1495,6 +1495,8 @@
 
 config MIPS_MT
 	bool "Enable MIPS MT"
+	depends on CPU_MIPS32_R2
+	#depends on CPU_MIPS64_R2		# later ...
 
 choice
 	prompt "MIPS MT options"