Convert CONFIG_SYS_I2C_SOFT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_SOFT
   CONFIG_SYS_I2C_SOFT_SPEED
   CONFIG_SYS_I2C_SOFT_SLAVE

Signed-off-by: Tom Rini <trini@konsulko.com>
17 files changed