soc/intel/skylake: Add proper support to enable UART2 in 16550 mode

Need to perform a dummy read in order to activate LPSS UART's
16550 8-bit compatibility mode.

TEST=Able to get serial log in both 32 bit and 8 bit mode through
LPSS UART2 based on CONFIG_DRIVERS_UART_8250MEM_32 and
CONFIG_DRIVERS_UART_8250MEM selection.

Change-Id: I5f23fef4522743efd49167afb04d56032e16e417
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/20939
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed