Change mips64 default to mips64r6 from mips64r2

Also add back mips flags previously can't be handled by clang

See aosp/build
  13066a8d4c2f8ddb2348e6d3df3948a0f4dbf105
  10326b3d7f1966381812ef55478619f714917c23

Change-Id: Iedc8dadd24f72fbd9c5589eec34677c1827290f3
diff --git a/core/clang/mips.mk b/core/clang/mips.mk
index 1624b6f..08daf40 100644
--- a/core/clang/mips.mk
+++ b/core/clang/mips.mk
@@ -7,14 +7,6 @@
 # Include common unknown flags
 CLANG_CONFIG_mips_UNKNOWN_CFLAGS := \
   $(CLANG_CONFIG_UNKNOWN_CFLAGS) \
-  -mips32 \
-  -mips32r2 \
-  -mips32r6 \
-  -mfp32 \
-  -mfp64 \
-  -mfpxx \
-  -modd-spreg \
-  -mno-odd-spreg \
   -fno-strict-volatile-bitfields \
   -fgcse-after-reload \
   -frerun-cse-after-loop \
diff --git a/core/clang/mips64.mk b/core/clang/mips64.mk
index a76aa08..612175c 100644
--- a/core/clang/mips64.mk
+++ b/core/clang/mips64.mk
@@ -7,7 +7,6 @@
 # Include common unknown flags
 CLANG_CONFIG_mips64_UNKNOWN_CFLAGS := \
   $(CLANG_CONFIG_UNKNOWN_CFLAGS) \
-  -mips64r6 \
   -fno-strict-volatile-bitfields \
   -fgcse-after-reload \
   -frerun-cse-after-loop \
diff --git a/core/combo/TARGET_linux-mips64.mk b/core/combo/TARGET_linux-mips64.mk
index 938b11c..4511b47 100644
--- a/core/combo/TARGET_linux-mips64.mk
+++ b/core/combo/TARGET_linux-mips64.mk
@@ -31,7 +31,7 @@
 # version.
 #
 ifeq ($(strip $(TARGET_ARCH_VARIANT)),)
-TARGET_ARCH_VARIANT := mips64r2
+TARGET_ARCH_VARIANT := mips64r6
 endif
 
 # Decouple NDK library selection with platform compiler version
diff --git a/target/board/generic_mips64/BoardConfig.mk b/target/board/generic_mips64/BoardConfig.mk
index 5dc943a..f8cf4f0 100644
--- a/target/board/generic_mips64/BoardConfig.mk
+++ b/target/board/generic_mips64/BoardConfig.mk
@@ -24,7 +24,7 @@
 
 TARGET_ARCH := mips64
 ifeq (,$(TARGET_ARCH_VARIANT))
-TARGET_ARCH_VARIANT := mips64r2
+TARGET_ARCH_VARIANT := mips64r6
 endif
 TARGET_CPU_ABI  := mips64