boards: Add support for Quark SE C1000_BLE

The Quark SE C1000 BLE Core is a nRF51822-QFAA, with 16kB of RAM and
256kB of flash. The configuration is otherwise similar to the Arduino
101 BLE, except that the UART RTS pin is the same as that used by
nrf51_pca10028.

Change-Id: I88cb18876bdde65abcf9a499894f70802046c824
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>