I2C: extEEPROM test failed on Nucleo L152RE

[fpistm]

Since this #135, extEEPROM test failed on Nucleo L152RE

[fpistm]

Will be covered by #217

[LMESTM]

@fpistm few observations:

• I reproduced the issue of eeprom test failing with L152RE
• if using a digital probe to debug, the problem disappear ... hmmm
• if changing timing setting from I2C_DUTYCYCLE_2 to I2C_DUTYCYCLE_16_9 it works fine as well ...

to be continued !