samd: Simplify the pin-af-table handling.

- The pin-af-table-SAMDxx.csv file are moved to the variants
  directories with the name as pin-af-table.csv.
- The handling in Makefile and pin_af.c is simplified.

ports/samd/Makefile

@@ -47,7 +47,7 @@ INC += -I$(TOP)/lib/asf4/$(MCU_SERIES_LOWER)/include/pio
 INC += -I$(TOP)/lib/tinyusb/src
 
 MAKE_PIN_AF = boards/make-pin-af.py
-PIN_AF_TABLE_CSV = boards/pin-af-table-$(MCU_SERIES).csv
+PIN_AF_TABLE_CSV = variants/$(MCU_SERIES_LOWER)/pin-af-table.csv
 GEN_PIN_AF = pin_af_table.c
 
 MAKE_PINS = boards/make-pins.py
@@ -61,7 +61,6 @@ CFLAGS = $(INC) -Wall -Werror -std=c99 -nostdlib -mthumb $(CFLAGS_MCU_$(MCU_SERI
 CFLAGS += -DMCU_$(MCU_SERIES) -D__$(CMSIS_MCU)__
 CFLAGS += $(CFLAGS_MOD) $(CFLAGS_EXTRA)
 CFLAGS += -DMPCONFIG_MCU_H='<boards/mpconfig_$(MCU_SERIES_LOWER).h>'
-CFLAGS += -DPIN_AF_TABLE_C='<$(BUILD)/$(GEN_PIN_AF)>'
 
 LDFLAGS = -nostdlib $(addprefix -T,$(LD_FILES)) -Map=$@.map --cref
 LDFLAGS += $(LDFLAGS_MOD)

ports/samd/pin_af.c

@@ -38,7 +38,7 @@
 
 extern const uint8_t tcc_channel_count[];
 
-#include PIN_AF_TABLE_C
+#include "pin_af_table.c"
 
 // Just look for an table entry for a given pin and raise an error
 // in case of no match (which should not happen).