sys/ztimer: select ztimer_periph_no_rtt only for samd21

cpu/sam0_common/Kconfig

@@ -27,7 +27,6 @@ config CPU_COMMON_SAM0
     select HAS_PERIPH_WDT_CB
     select HAS_PERIPH_WDT_WARNING_PERIOD
     select HAVE_SHARED_PERIPH_RTT_PERIPH_RTC
-    select MODULE_ZTIMER_NO_PERIPH_RTT if TEST_KCONFIG && MODULE_ZTIMER
 
     select MODULE_PERIPH_SPI_GPIO_MODE if MODULE_PERIPH_SPI && HAS_PERIPH_SPI_GPIO_MODE
 

cpu/sam3/Kconfig

@@ -12,7 +12,6 @@ config CPU_FAM_SAM3
     select HAS_CPU_SAM3
     select HAS_PERIPH_CPUID
     select HAS_PERIPH_HWRNG
-    select MODULE_ZTIMER_NO_PERIPH_RTT if TEST_KCONFIG && MODULE_ZTIMER
 
 ## CPU Models
 config CPU_MODEL_SAM3X8E

cpu/samd21/Kconfig

@@ -11,6 +11,7 @@ config CPU_COMMON_SAMD21
     select CPU_CORE_CORTEX_M0PLUS
     select HAS_CPU_SAMD21
     select HAS_PERIPH_GPIO_FAST_READ
+    select MODULE_ZTIMER_NO_PERIPH_RTT if TEST_KCONFIG && MODULE_ZTIMER
 
 config CPU_FAM_SAMD10
     bool

sys/ztimer/Makefile.dep

@@ -81,11 +81,11 @@ endif
 # NOTE: select the module here and not in the CPU so that order of inclusion
 # does not have periph_rtt selected earlier that it should be while at the same
 # time avoiding the module 'ztimer-no_periph_rtt' being included unecesarily.
-# The sam0 rtt busy loops for 180us every time an alarm is set or
+# The samd21 rtt busy loops for 180us every time an alarm is set or
 # the counter is read, this propagates and leads to timing errors
 # on ztimer_msec that are higher than > +-1msec.
 # The same goes for the fe310 rtt.
-ifneq (,$(filter sam% fe310,$(CPU)))
+ifneq (,$(filter samd21 fe310,$(CPU)))
   USEMODULE += ztimer_no_periph_rtt
 endif