microblaze: Enable SERIAL_OF_PLATFORM

SERIAL_OF_PLATFORM is required for getting 8250 to work.
Reported-by: Subbaraya Sundeep Bhatta <sbhatta@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/configs/mmu_defconfig

@@ -49,6 +49,7 @@ CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_UARTLITE=y
 CONFIG_SERIAL_UARTLITE_CONSOLE=y
+CONFIG_SERIAL_OF_PLATFORM=y
 # CONFIG_HW_RANDOM is not set
 CONFIG_XILINX_HWICAP=y
 CONFIG_I2C=y

arch/microblaze/configs/nommu_defconfig

@@ -58,6 +58,7 @@ CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_UARTLITE=y
 CONFIG_SERIAL_UARTLITE_CONSOLE=y
+CONFIG_SERIAL_OF_PLATFORM=y
 # CONFIG_HW_RANDOM is not set
 CONFIG_XILINX_HWICAP=y
 CONFIG_I2C=y