ports: Switch build to use common lib/libm list of source files.

Signed-off-by: Damien George <damien@micropython.org>

ports/samd/Makefile

@@ -142,35 +142,8 @@ ASF4_SRC_C += $(addprefix lib/asf4/$(MCU_SERIES_LOWER)/,\
 	hpl/nvmctrl/hpl_nvmctrl.c \
 	)
 
-LIBM_SRC_C += $(addprefix lib/libm/,\
-	acoshf.c \
-	asinfacosf.c \
-	asinhf.c \
-	atan2f.c \
-	atanf.c \
-	atanhf.c \
-	ef_rem_pio2.c \
-	ef_sqrt.c \
-	erf_lgamma.c \
-	fmodf.c \
-	kf_cos.c \
-	kf_rem_pio2.c \
-	kf_sin.c \
-	kf_tan.c \
-	log1pf.c \
-	math.c \
-	nearbyintf.c \
-	roundf.c \
-	sf_cos.c \
-	sf_erf.c \
-	sf_frexp.c \
-	sf_ldexp.c \
-	sf_modf.c \
-	sf_sin.c \
-	sf_tan.c \
-	wf_lgamma.c \
-	wf_tgamma.c \
-	)
+LIBM_SRC_C += $(SRC_LIB_LIBM_C)
+LIBM_SRC_C += $(SRC_LIB_LIBM_SQRT_SW_C)
 
 TINYUSB_SRC_C += $(addprefix lib/tinyusb/src/,\
 	class/cdc/cdc_device.c \