OpenULINK firmware: fix name of USB Jump Table symbol

OpenULINK firmware: fix name of USB Jump Table symbol

Fix a case mistake in the name of the USB Jump Table ("USB_jump_table"
vs. "USB_Jump_Table") which led to an assembler error when attempting
to build the firmware with recent SDCC versions, because the assembler
now treats symbol names as case-sensitive.

Successfully tested with ULINK probe and STM32F103 (debug, erase and write
flash).

Change-Id: I979667b9130efcdccc3ac73269c38f06e0590048
Signed-off-by: Martin Schmölzer <martin.schmoelzer@student.tuwien.ac.at>
Reviewed-on: http://openocd.zylin.com/1482
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>