configs: visionfive2: Disable ENV_IS_NOWHERE

configs: visionfive2: Disable ENV_IS_NOWHERE

The VisionFive 2 board supports saving the u-boot environment settings
are saved to on-board SPI flash. However the defconfig enables both
ENV_IS_NOWHERE and ENV_IS_IN_SPI_FLASH, preventing the "saveenv" command
to work. Fix that by disabling ENV_IS_NOWHERE.

Fixes: 7d79bed00c9e ("configs: starfive: Enable environment in SPI flash support")
Reported-by: E Shattow <lucent@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>