doc/drivers/sys: fixed all refs to drivers_periph_xx

doc/doxygen/src/mainpage.md

@@ -138,7 +138,7 @@ switching) code. For most CPUs you will also find the linker scripts in the
 `ldscripts` sub-directory.
 
 In the `periph` sub-directory of each CPU you can find the implementations of
-the CPU's peripheral drivers like SPI, UART, GPIO, etc.  See @ref driver_periph
+the CPU's peripheral drivers like SPI, UART, GPIO, etc.  See @ref drivers_periph
 for their API documentation.
 
 Many CPUs share a certain amount of their code (e.g. all ARM Cortex-M based

drivers/include/adc_legacy.h

@@ -10,8 +10,8 @@
  * @defgroup    drivers_adc ADC
  * @ingroup     drivers
  * @brief       Generic interface for ADC drivers
- * @deprecated  This interface is obsolete. Use the @ref driver_periph_adc
- *              interface in @ref driver_periph instead.
+ * @deprecated  This interface is obsolete. Use the @ref drivers_periph_adc
+ *              interface in @ref drivers_periph instead.
  *
  * @author      Oliver Hahm <oliver.hahm@inria.fr>
  *

sys/include/net/gnrc/slip.h

@@ -10,7 +10,7 @@
  * @defgroup    net_gnrc_slip SLIP
  * @ingroup     net_gnrc
  * @brief       Provides a SLIP interface over UART utilizing
- *              @ref driver_periph_uart.
+ *              @ref drivers_periph_uart.
  * @see         <a href="https://www.ietf.org/rfc/rfc1055">RFC 1055</a>
  * @{
  *