MIPS: unify CPU code in arch/mips/cpu/

Unify and move code in arch/mips/cpu/mips[32|64]/ to arch/mips/cpu/.
The CPU specific config.mk files need to remain until
CONFIG_STANDALONE_LOAD_ADDR is converted to a global Kconfig symbol.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index ff01bfe..43f0f5c 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -2,11 +2,9 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-head-$(CONFIG_CPU_MIPS32) := arch/mips/cpu/mips32/start.o
-head-$(CONFIG_CPU_MIPS64) := arch/mips/cpu/mips64/start.o
+head-y := arch/mips/cpu/start.o
 
-libs-$(CONFIG_CPU_MIPS32) += arch/mips/cpu/mips32/
-libs-$(CONFIG_CPU_MIPS64) += arch/mips/cpu/mips64/
+libs-y += arch/mips/cpu/
 libs-y += arch/mips/lib/
 
 libs-$(CONFIG_SOC_AU1X00) += arch/mips/mach-au1x00/