spi: s3c64xx: remove redundant pointer sci

The pointer sci is assigned but never read, hence it is redundant
and can be removed. Cleans up clang warning:

drivers/spi/spi-s3c64xx.c:791:2: warning: Value stored to 'sci' is
never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Mark Brown <broonie@kernel.org>