arm: mvebu: Use 4K sector for Thecus N2350 SPI flash

Since the SPI flash chip mx25l3205d on this board has 4K-sector
capability, enable it for the envs.

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
1 file changed