remove RISCV64_ZVL256B additional extentions

Makefile.prebuild

@@ -60,7 +60,7 @@ TARGET_FLAGS = -march=rv64imafdcv_zba_zbb_zfh -mabi=lp64d
 endif
 
 ifeq ($(TARGET), RISCV64_ZVL256B)
-TARGET_FLAGS = -march=rv64imafdcv_zba_zbb_zfh -mabi=lp64d
+TARGET_FLAGS = -march=rv64imafdcv -mabi=lp64d
 endif
 
 ifeq ($(TARGET), RISCV64_ZVL128B)

Makefile.riscv64

@@ -7,8 +7,8 @@ CCOMMON_OPT += -march=rv64imafdcv_zba_zbb_zfh_zvl512b -mabi=lp64d -ffast-math
 FCOMMON_OPT += -march=rv64imafdcv_zba_zbb_zfh -mabi=lp64d -static
 endif
 ifeq ($(CORE), RISCV64_ZVL256B)
-CCOMMON_OPT += -march=rv64imafdcv_zba_zbb_zfh_zvl256b -mabi=lp64d
-FCOMMON_OPT += -march=rv64imafdcv_zba_zbb_zfh -mabi=lp64d -static
+CCOMMON_OPT += -march=rv64imafdcv_zvl256b -mabi=lp64d
+FCOMMON_OPT += -march=rv64imafdcv -mabi=lp64d -static
 endif
 ifeq ($(CORE), RISCV64_ZVL128B)
 CCOMMON_OPT += -march=rv64imafdcv -mabi=lp64d