Merge pull request #7359 from fiveangle/pio_printrboard_revf

Add PIO entry for PRINTRBOARD_REVF

platformio.ini

 #board_f_cpu = 20000000L
 lib_deps = ${common.lib_deps}
 
+[env:printrboard_revf]
+platform = teensy
+framework = arduino
+board = teensy20pp
+build_flags = -I $BUILDSRC_DIR -D MOTHERBOARD=BOARD_PRINTRBOARD_REVF
+lib_deps = ${common.lib_deps}
+
 [env:brainwavepro]
 platform = teensy
 framework = arduino