boards/arduino101: Enable UART 0 controller

boards/x86/arduino_101/arduino_101_defconfig currently enables
CONFIG_UART_QMSI_0_HW_FC (HW flow control on UART 0), but doesn't enable
CONFIG_UART_QMSI_0 (the UART itself), which is a direct dependency.

This means CONFIG_UART_QMSI_0_HW_FC remains disabled despite the request
to enable it, and kconfig.py prints a warning.

Enable CONFIG_UART_QMSI_0 in the arduino_101_defconfig.

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
diff --git a/boards/x86/arduino_101/arduino_101_defconfig b/boards/x86/arduino_101/arduino_101_defconfig
index 9d03f09..77b3fda 100644
--- a/boards/x86/arduino_101/arduino_101_defconfig
+++ b/boards/x86/arduino_101/arduino_101_defconfig
@@ -7,6 +7,7 @@
 CONFIG_UART_CONSOLE=y
 CONFIG_SERIAL=y
 CONFIG_UART_QMSI=y
+CONFIG_UART_QMSI_0=y
 CONFIG_UART_QMSI_0_HW_FC=y
 CONFIG_PRINTK=y
 CONFIG_PINMUX=y