Remove MIPS architecture

The MIPS architecture port has been added 5+ years ago in order to
support a Chrome OS project that ended up going nowhere. No other board
has used it since and nobody is still willing or has the expertise and
hardware to maintain it. We have decided that it has become too much of
a mainenance burden and the chance of anyone ever reviving it seems too
slim at this point. This patch eliminates all MIPS code and
MIPS-specific hacks.

Change-Id: I5e49451cd055bbab0a15dcae5f53e0172e6e2ebe
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34919
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/xcompile/xcompile

@@ -195,14 +195,6 @@ detect_special_flags() {
 		  "$LDFLAGS --fix-cortex-a53-843419" && \
 		  LDFLAGS_ARM64_A53_ERRATUM_843419+=" --fix-cortex-a53-843419"
 		;;
-	mipsel)
-		testcc "$GCC" "$CFLAGS_GCC -mno-abicalls -fno-pic" && \
-		  CFLAGS_GCC+=" -mno-abicalls -fno-pic"
-
-		# Enforce little endian mode.
-		testcc "$GCC" "$CFLAGS_GCC -EL" && \
-		  CFLAGS_GCC+=" -EL"
-		;;
 	esac
 }
 
@@ -314,7 +306,7 @@ EOF
 }
 
 # Architecture definitions
-SUPPORTED_ARCHITECTURES="arm arm64 mipsel riscv x64 x86 ppc64"
+SUPPORTED_ARCHITECTURES="arm arm64 riscv x64 x86 ppc64"
 
 # TARCH: local name for the architecture
 # (used as CC_${TARCH} in the build system)
@@ -367,16 +359,6 @@ arch_config_x86() {
 	CC_RT_EXTRA_GCC="--wrap __divdi3 --wrap __udivdi3 --wrap __moddi3 --wrap __umoddi3"
 }
 
-arch_config_mipsel() {
-	TARCH="mips"
-	TBFDARCHS="tradlittlemips littlemips"
-	TCLIST="mipsel"
-	TWIDTH="32"
-	TSUPP="mips mipsel"
-	TABI="elf"
-	TENDIAN="EL"
-}
-
 arch_config_ppc64() {
 	TARCH="ppc64"
 	TBFDARCHS="powerpc"