spi: s3c64xx: do not configure the device twice

At the start of the transfer, the spi_config function is called
twice, the first time when the 3c64xx_spi_prepare_message is
called and the second time with the s3c64xx_spi_transfer_one,
both called from the spi framework.

Remove the first call at the prepare message because in that
point we don't have the imformation about "bit per word" and
frequency.

Signed-off-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>