DM: fix linker vfp arguments

Author: deanm1278

boards.txt

@@ -185,7 +185,7 @@ adafruit_metro_m4.build.vid=0x239A
 adafruit_metro_m4.build.pid=0x8020
 adafruit_metro_m4.bootloader.tool=openocd
 adafruit_metro_m4.bootloader.file=metroM4/METRO_M4_sam_ba.bin
-adafruit_metro_m4.compiler.arm.cmsis.ldflags="-L{build.variant.path}" -larm_cortexM4lf_math
+adafruit_metro_m4.compiler.arm.cmsis.ldflags="-L{build.variant.path}" -larm_cortexM4lf_math -mfloat-abi=hard -mfpu=fpv4-sp-d16
 
 # Adafruit Feather M4 (SAMD51)
 # ------------------------------
@@ -215,4 +215,4 @@ adafruit_feather_m4.build.vid=0x239A
 adafruit_feather_m4.build.pid=0x8022
 adafruit_feather_m4.bootloader.tool=openocd
 adafruit_feather_m4.bootloader.file=metroM4/FEATHER_M4_sam_ba.bin
-adafruit_feather_m4.compiler.arm.cmsis.ldflags="-L{build.variant.path}" -larm_cortexM4lf_math
+adafruit_feather_m4.compiler.arm.cmsis.ldflags="-L{build.variant.path}" -larm_cortexM4lf_math -mfloat-abi=hard -mfpu=fpv4-sp-d16