i2c: config: Move SYS_I2C_DW to Kconfig

This patch moves all appearances of CONFIG_SYS_I2C_DW from the config
header to the defconfig files.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/configs/socfpga_socrates_defconfig b/configs/socfpga_socrates_defconfig
index a17e9d0..b47a560 100644
--- a/configs/socfpga_socrates_defconfig
+++ b/configs/socfpga_socrates_defconfig
@@ -34,6 +34,7 @@
 CONFIG_CMD_FS_GENERIC=y
 CONFIG_SPL_DM_SEQ_ALIAS=y
 CONFIG_DWAPB_GPIO=y
+CONFIG_SYS_I2C_DW=y
 CONFIG_DM_MMC=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y