cpu/stm32l0: add definitions for internal eeprom

cpu/stm32l0/Makefile.features

 FEATURES_PROVIDED += periph_flash_common
 FEATURES_PROVIDED += periph_flashpage
 FEATURES_PROVIDED += periph_flashpage_raw
+FEATURES_PROVIDED += periph_eeprom
 FEATURES_PROVIDED += periph_hwrng
 
 BOARDS_WITHOUT_HWRNG += nucleo-l031k6

cpu/stm32l0/include/cpu_conf.h

@@ -79,6 +79,20 @@ extern "C" {
 #define FLASHPAGE_RAW_ALIGNMENT    (4U)
 /** @} */
 
+/**
+ * @name    EEPROM configuration
+ * @{
+ */
+#define EEPROM_START_ADDR          (0x08080000)
+#if defined(CPU_MODEL_STM32L073RZ) || defined(CPU_MODEL_STM32L072CZ)
+#define EEPROM_SIZE                (6144U)  /* 6kB */
+#elif defined(CPU_MODEL_STM32L053R8)
+#define EEPROM_SIZE                (2048U)  /* 2kB */
+#elif defined(CPU_MODEL_STM32L031K6)
+#define EEPROM_SIZE                (1024U)  /* 1kB */
+#endif
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif