test/coap: update blacklist for features

Boards that don't have a transceiver are automatically filtered out already.

tests/coap/Makefile

 APPLICATION = coap
 include ../Makefile.tests_common
 
-BOARD_BLACKLIST := arduino-due chronos mbed_lpc1768 msb-430 msb-430h qemu-i386 stm32f0discovery \
-                   stm32f3discovery stm32f4discovery telosb wsn430-v1_3b wsn430-v1_4 udoo z1 \
-                   pca10000 pca10005 arduino-mega2560 msbiot yunjia-nrf51822 samr21-xpro
-#arduino-mega2560: missing header sys/types.h
-#MSP boards: no assert.h
-#rest: no radio
+# the MSP430 toolchain does not include assert.h
+BOARD_BLACKLIST := chronos msb-430 msb-430h telosb wsn430-v1_3b wsn430-v1_4 z1
 
 BOARD_INSUFFICIENT_RAM := redbee-econotag