tcl/board: Clean up STM32 EVAL boards configurations

Make consistent use of hex memory size for flashing.

Delete stm32f10x_128k_eval.cfg. It has no product reference
nor any settings in it.

tcl/board/stm32100b_eval.cfg

 # This is an STM32 eval board with a single STM32F100VBT6 chip.
 # http://www.st.com/internet/evalboard/product/247099.jsp
 
-# we only have 8k sram
-set WORKAREASIZE 8192
+# The chip has only 8KB sram
+set WORKAREASIZE 0x2000
 
 source [find target/stm32.cfg]

tcl/board/stm3210b_eval.cfg

 # This is an STM32 eval board with a single STM32F10x (128KB) chip.
 # http://www.st.com/internet/evalboard/product/176090.jsp
 
-# increase working area for faster flash programming
-
-set WORKAREASIZE 32768
+# increase working area to 32KB for faster flash programming
+set WORKAREASIZE 0x8000
 
 source [find target/stm32.cfg]

tcl/board/stm3210c_eval.cfg

 # This is an STM32 eval board with a single STM32F107VCT chip.
 # http://www.st.com/internet/evalboard/product/217965.jsp
 
-# increase working area for faster flash programming
-
-set WORKAREASIZE 32768
+# increase working area to 32KB for faster flash programming
+set WORKAREASIZE 0x8000
 
 source [find target/stm32.cfg]

tcl/board/stm3210e_eval.cfg

 # This is an STM32 eval board with a single STM32F103ZET6 chip.
 # http://www.st.com/internet/evalboard/product/204176.jsp
 
-# increase working area for faster flash programming
-
-set WORKAREASIZE 32768
+# increase working area to 32KB for faster flash programming
+set WORKAREASIZE 0x8000
 
 source [find target/stm32.cfg]
 

tcl/board/stm32f10x_128k_eval.cfg

-# This is an STM32 eval board with a single STM32F103VBT6 chip on it.
-
-source [find target/stm32.cfg]
-