util/amdfwtool: Add "all" target to Makefile

The test-tools make target requires it.

Change-Id: I20819f8d587e6b3a472cdc32751e9edf505d5ba6
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49962
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

util/amdfwtool/Makefile

@@ -7,6 +7,7 @@ OBJ = $(SRC:%.c=%.o)
 TARGET = amdfwtool
 CFLAGS=-O2 -Wall -Wextra -Wshadow
 
+all: $(TARGET)
 
 $(TARGET): $(OBJ)
 	$(CC) $(OBJ) $(LDFLAGS) -o $@