xcompile: switch around armv7 TCARCHes

clang probing will pick up the first one that clang does not complain about
and right now that is armv7a-eabi, even though our toolchain builds for
armv7-a-eabi (and consecutively the build fails because there is no
armv7a-eabi-as)

Change-Id: I2594151150107f8e9c1aad33647dcb2f9878f953
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10830
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/xcompile/xcompile

@@ -208,7 +208,7 @@ SUPPORTED_ARCHITECTURES="arm arm64 mipsel riscv x64 x86"
 arch_config_arm() {
 	TARCH="arm"
 	TBFDARCHS="littlearm"
-	TCLIST="armv7a armv7-a"
+	TCLIST="armv7-a armv7a"
 	TWIDTH="32"
 	TSUPP="arm armv4 armv7 armv7_m"
 	TABI="eabi"