arm64: defconfig: enable HW random as module

drivers/char/hw_random/Kconfig has 'default m', so
simply removing this entry from the defconfig will
enable building HW random drivers as modules.
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/configs/defconfig

@@ -223,7 +223,6 @@ CONFIG_SERIAL_XILINX_PS_UART=y
 CONFIG_SERIAL_XILINX_PS_UART_CONSOLE=y
 CONFIG_SERIAL_MVEBU_UART=y
 CONFIG_VIRTIO_CONSOLE=y
-# CONFIG_HW_RANDOM is not set
 CONFIG_I2C_CHARDEV=y
 CONFIG_I2C_MUX=y
 CONFIG_I2C_MUX_PCA954x=y