boards: revert forced use of periph_dma with STM32

The periph_dma is not pulled in automatically for all applications.
Applications willing to use the configured peripherals with periph_dma
for a given board will have to include the feature explictly in their
Makefile.

It was causing unrelated issues as threads got de-scheduled while
calling printf and this was not handled properly in tests at that
moment.

boards/b-l072z-lrwan1/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 ifneq (,$(filter netdev_default,$(USEMODULE)))
   USEMODULE += sx1276
 endif

boards/b-l475e-iot01a/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 ifneq (,$(filter saul_default,$(USEMODULE)))
   USEMODULE += saul_gpio
   USEMODULE += hts221

boards/iotlab-m3/Makefile.dep

 include $(RIOTBOARD)/common/iotlab/Makefile.dep
 
-FEATURES_REQUIRED += periph_dma
-
 ifneq (,$(filter saul_default,$(USEMODULE)))
   USEMODULE += isl29020
   USEMODULE += lps331ap

boards/nucleo-f091rc/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 include $(RIOTBOARD)/common/nucleo/Makefile.dep

boards/nucleo-f207zg/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 include $(RIOTBOARD)/common/nucleo/Makefile.dep

boards/nucleo-f767zi/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 include $(RIOTBOARD)/common/nucleo/Makefile.dep

boards/nucleo-l152re/Makefile.dep

-FEATURES_REQUIRED += periph_dma
-
 include $(RIOTBOARD)/common/nucleo/Makefile.dep