qemu-riscv: Fix issue with yocto having issue fetching qemu-riscv
qemu-riscv: Fix issue with yocto having issue fetching qemu-riscv

Since the SHA we want isn't in master it seemed to cause an issue with
fetching the repo.  Adding nobranch=1 fixes this.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

zephyrproject-rtos/meta-zephyr-sdk,zephyrproject-rtos/meta-zephyr-sdk,zephyrproject-rtos/meta-zephyr-sdk,zephyrproject-rtos/meta-zephyr-sdk