drivers/include/periph/eeprom: Changed uint8_t* to void* in API

[fabian18]

Contribution description

This tiny PR changes the EEPROM API for eeprom_read and eeprom_write
to expect void* data instead of uint8_t* data. This suggests a more general interface.

Testing procedure

I executed tests/eepreg and tests/periph_eeprom on arduino-mega2560.

Issues/PRs references

This PR has emerged from PR #11929 .

[maribu]

tests/periph_eeprom:

> write 0 Hallo
2019-08-09 18:12:46,228 - INFO #  write 0 Hallo
2019-08-09 18:12:46,269 - INFO # 5 bytes written to EEPROM
> read 0 5
2019-08-09 18:12:52,287 - INFO #  read 0 5
2019-08-09 18:12:52,327 - INFO # Data read from EEPROM (5 bytes): Hallo

tests/eepreg:

2019-08-09 18:13:50,484 - INFO # main(): This is RIOT! (Version: 2019.10-devel-365-g2c001-fabian)
2019-08-09 18:13:50,491 - INFO # EEPROM registry (eepreg) test routine
2019-08-09 18:13:50,573 - INFO # Testing new registry creation: reset check [SUCCESS]
2019-08-09 18:13:50,684 - INFO # Testing writing and reading entries: add write add read [SUCCESS]
2019-08-09 18:13:50,740 - INFO # Testing detection of conflicting size: add [SUCCESS]
2019-08-09 18:13:50,790 - INFO # Testing calculation of lengths: len len [SUCCESS]
2019-08-09 18:13:51,073 - INFO # Testing of successful data move after rm: rm read data [SUCCESS]
2019-08-09 18:13:51,162 - INFO # Testing of free space change after write: free add free [SUCCESS]
2019-08-09 18:13:51,224 - INFO # Testing of iteration over registry: iter bar foo [SUCCESS]
2019-08-09 18:13:51,240 - INFO # Tests complete!

[maribu]

As this is an API change, 2 ACKs are formally required. (This change will not break any caller, as uint8_t * can be implicitly casted to void *.)

@benpicco: Mind to have a look?

[maribu]

ACK (1/2)

[benpicco]

Looks good. Interestingly both implementations already cast the argument to uint8_t* internally, so there really is no semantic change here.