flash/stm32f1x: add support for RISC-V GigaDevice GD32VF103

The device has compatible flash macro with STM32F1 family, reuse
stm32f1x driver code.

Detect non-ARM target - for simplicy test target type name 'riscv'
and the address has 32 bits.

In case of RISC-V CPU use simple chunked write algo - async algo
cannot be used as the core implemented in this device doesn't
allow memory access while running.

Change-Id: Ie3886fbd8573652691f91a02335812a7300689f7
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/6704
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@sifive.com>

contrib/loaders/flash/gd32vf103/Makefile

@@ -0,0 +1,28 @@
+BIN2C = ../../../../src/helper/bin2char.sh
+
+CROSS_COMPILE ?= riscv-none-embed-
+
+CC=$(CROSS_COMPILE)gcc
+OBJCOPY=$(CROSS_COMPILE)objcopy
+OBJDUMP=$(CROSS_COMPILE)objdump
+
+CFLAGS = -march=rv32i -mabi=ilp32 -static -nostartfiles -nostdlib -Os -g -fPIC
+
+all: gd32vf103.inc
+
+.PHONY: clean
+
+%.elf: %.c
+	$(CC) $(CFLAGS) $< -o $@
+
+%.lst: %.elf
+	$(OBJDUMP) -S $< > $@
+
+%.bin: %.elf
+	$(OBJCOPY) -Obinary $< $@
+
+%.inc: %.bin
+	$(BIN2C) < $< > $@
+
+clean:
+	-rm -f *.elf *.lst *.bin *.inc