drivers: fix doxygen grouping

drivers/adcxx1c/adcxx1c.c

drivers/adcxx1c/include/adcxx1c_params.h

drivers/adcxx1c/include/adcxx1c_regs.h

drivers/include/adcxx1c.h

drivers/include/net/netdev/eth.h

drivers/include/net/netdev/ieee802154.h

drivers/include/tja1042.h

drivers/isl29020/include/isl29020-internal.h

drivers/kw2xrf/include/kw2xrf_tm.h

drivers/lsm303dlhc/include/lsm303dlhc-internal.h

drivers/mma8x5x/include/mma8x5x_regs.h

drivers/mma8x5x/mma8x5x_saul.c

drivers/netdev_eth/netdev_eth.c

drivers/netdev_ieee802154/netdev_ieee802154.c

drivers/nvram/nvram-vfs.c

drivers/nvram_spi/nvram-spi.c