Reduce Teensy++ 2.0 to a single entry

Followup to #7750, #7826

platformio.ini

 src_filter  = ${common.default_src_filter}
 
 #
-# PrintrBoard (Teensy++ 2.0)
+# Teensy++ 2.0
 #
-[env:printrboard]
+# - PrintrBoard
+# - PrintrBoard Rev.F
+# - Brainwave Pro
+#
+[env:teensy20]
 platform      = teensy
 framework     = arduino
 board         = teensy20pp
-build_flags   = -I $BUILDSRC_DIR -D MOTHERBOARD=BOARD_PRINTRBOARD
+build_flags   = -I $BUILDSRC_DIR
 #board_f_cpu  = 20000000L     ; Bug in Arduino framework disallows boards running at 20Mhz
 lib_deps      = ${common.lib_deps}
 src_filter    = ${common.default_src_filter}
 
 #
-# PrintrBoard Rev.F (Teensy++ 2.0)
-#
-[env:printrboard_revf]
-platform    = teensy
-framework   = arduino
-board       = teensy20pp
-build_flags = -I $BUILDSRC_DIR -D MOTHERBOARD=BOARD_PRINTRBOARD_REVF
-lib_deps    = ${common.lib_deps}
-src_filter  = ${common.default_src_filter}
-
-#
-# Brainwave Pro (Teensy++ 2.0)
-#
-[env:brainwavepro]
-platform    = teensy
-framework   = arduino
-board       = teensy20pp
-build_flags = -I $BUILDSRC_DIR -D MOTHERBOARD=BOARD_BRAINWAVE_PRO
-lib_deps    = ${common.lib_deps}
-src_filter  = ${common.default_src_filter}
-
-#
 # RAMBo
 #
 [env:rambo]