Added STM32L053R8

Hello, checked this board with stink. It communicates without flaw with the board:

```
2015-12-15T14:47:03 INFO src/stlink-common.c: Loading device parameters....
2015-12-15T14:47:03 INFO src/stlink-common.c: Device connected is: L0x3 device, id 0x10086417
2015-12-15T14:47:03 INFO src/stlink-common.c: SRAM size: 0x2000 bytes (8 KiB), Flash: 0x10000 bytes (64 KiB) in pages of 128 bytes
2015-12-15T14:47:03 INFO gdbserver/gdb-server.c: Chip ID is 00000417, Core ID is  0bc11477.
2015-12-15T14:47:03 INFO gdbserver/gdb-server.c: Target voltage is 3264 mV.
2015-12-15T14:47:03 INFO gdbserver/gdb-server.c: Listening at *:4242...
```

When I launch GDB and connect to the server, I get :

```
2015-12-15T14:51:41 ERROR gdbserver/gdb-server.c: [FP_CTRL] = 0x00000041 expecting 0x00000261
2015-12-15T14:51:41 INFO gdbserver/gdb-server.c: GDB connected.
```

on the st-util side and :

```
Cannot access memory at address 0xffffffff
```

on the GDB side

Reading and writing to memory and registers works however I get 

```
Cannot access memory at address 0xffffffff
```

Each time I write to the memory or to a register