Invalid I2C sensors values on iotlab-m3

Description

The I2C sensors on the iotlab-m3 are broken in master. Bisecting returns that fb38cf37fdad543e11c28d48eb9f2376848f90b8 from #12007 is the culprit.

CC'ing @MrKevinWeiss since you seem to have introduced the problem. Maybe this is a more general problem with the I2C driver on stm32f1 ?

Steps to reproduce the issue

Start an experiment with one iotlab-m3

$ iotlab-experiment submit -n "" -d 120 -l 1,archi=m3:at86rf231+site=saclay
$ iotlab-experiment wait

Flash examples/saul on the device:

$ make BOARD=iotlab-m3 IOTLAB_NODE=auto-ssh -C examples/saul flash term

Play with saul:
```
> saul
```
on master the lps331ap sensor doesn't appear in the list although it should (it works with 2019.10-branch) reading the lsm303dlhc returns invalid values

Expected results

lps331ap sensor appears in the list, values of sensors seems correct.

Actual results

on master the lps331ap sensor doesn't appear in the list although it should (it works with 2019.10-branch) reading the lsm303dlhc returns invalid values

Versions

$ make print-versions

``` Operating System Environment ----------------------------- Operating System: "Ubuntu" "19.04 (Disco Dingo)" Kernel: Linux 5.0.0-32-generic x86_64 x86_64 Installed compiler toolchains ----------------------------- native gcc: gcc (Ubuntu 8.3.0-6ubuntu1) 8.3.0 arm-none-eabi-gcc: arm-none-eabi-gcc (GNU Tools for Arm Embedded Processors 8-2019-q3-update) 8.3.1 20190703 (release) [gcc-8-branch revision 273027] avr-gcc: avr-gcc (AVR_8_bit_GNU_Toolchain_3.6.2_1759) 5.4.0 mips-mti-elf-gcc: mips-mti-elf-gcc (Codescape GNU Tools 2016.05-03 for MIPS MTI Bare Metal) 4.9.2 msp430-gcc: missing riscv-none-embed-gcc: riscv-none-embed-gcc (GNU MCU Eclipse RISC-V Embedded GCC, 64-bit) 8.2.0 xtensa-esp32-elf-gcc: missing xtensa-lx106-elf-gcc: missing clang: clang version 8.0.0-3 (tags/RELEASE_800/final) Installed compiler libs ----------------------- arm-none-eabi-newlib: "3.1.0" mips-mti-elf-newlib: "2.1.0" riscv-none-embed-newlib: "3.0.0" xtensa-esp32-elf-newlib: missing xtensa-lx106-elf-newlib: missing avr-libc: "2.0.0" ("20150208") Installed development tools --------------------------- cmake: cmake version 3.13.4 cppcheck: Cppcheck 1.86 doxygen: 1.8.13 git: git version 2.20.1 make: GNU Make 4.2.1 openocd: Open On-Chip Debugger 0.10.0+dev-00930-g09eb941c (2019-09-11-15:06) python: Python 2.7.16 python2: Python 2.7.16 python3: Python 3.7.3 flake8: 3.7.7 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.7.3 on Linux coccinelle: spatch version 1.0.4 with Python support and with PCRE support ```

RIOT-OS / RIOT