MIPS: Make a alias for pistachio_defconfig

For those who miss the old defconfig, make a alias to generic
kernel.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Makefile

@@ -560,6 +560,9 @@ sead3micro_defconfig-y		:= micro32r2el_defconfig BOARDS=sead-3
 legacy_defconfigs		+= xilfpga_defconfig
 xilfpga_defconfig-y		:= 32r2el_defconfig BOARDS=xilfpga
 
+legacy_defconfigs		+= pistachio_defconfig
+pistachio_defconfig-y		:= 32r2el_defconfig BOARDS=marduk
+
 .PHONY: $(legacy_defconfigs)
 $(legacy_defconfigs):
 	$(Q)$(MAKE) -f $(srctree)/Makefile $($@-y)