i2c: Select SYS_I2C_DW_ENABLE_STATUS_UNSUPPORTED for SPEAr

The DW I2C controller in the SPEAr SoCs doesn't support the enable
status register check. This patch selects
SYS_I2C_DW_ENABLE_STATUS_UNSUPPORTED for these boards.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Heiko Schocher <hs@denx.de>