Fix ttgo twatch & tbeam board definition error

Author: lewis he

Diff for: boards.txt

@@ -3544,8 +3544,8 @@ t-beam.serial.disableRTS=true
 
 t-beam.build.mcu=esp32
 t-beam.build.core=esp32
-t-beam.build.variant=t-beam
-t-beam.build.board=T-Beam
+t-beam.build.variant=tbeam
+t-beam.build.board=TBeam
 
 t-beam.build.f_cpu=240000000L
 t-beam.build.flash_mode=dio
@@ -4100,7 +4100,7 @@ ttgo-t-watch.serial.disableRTS=true
 ttgo-t-watch.build.mcu=esp32
 ttgo-t-watch.build.core=esp32
 ttgo-t-watch.build.variant=twatch
-ttgo-t-watch.build.board=T-Watch
+ttgo-t-watch.build.board=TWatch
 
 ttgo-t-watch.build.f_cpu=240000000L
 ttgo-t-watch.build.flash_size=16MB