Remove features/tic6x-*.c files

Remove features/tic6x-*.c files

features/*.c are generated from *.xml files, in order to get pre-defined
target descriptions, (for native debugging, for example).  However, these
pre-generated tdesc_tic6x_* are not used in GDB at all.  This patch removes
features/tic6x-*.c files.

gdb:

2017-10-16  Yao Qi  <yao.qi@linaro.org>

	* features/Makefile (XMLTOC): Remove tic6x-*.xml.
	* features/tic6x-c62x.c: Remove.
	* features/tic6x-c64x-linux.c: Remove.
	* features/tic6x-c64x.c: Remove.
	* features/tic6x-c64xp-linux.c: Remove.
	* features/tic6x-c64xp.c: Remove.
	* tic6x-linux-tdep.c (_initialize_tic6x_linux_tdep): Don't call
	initialize_tdesc_tic6x_*_linux functions.
	* tic6x-tdep.c (_initialize_tic6x_tdep): Don't call
	initialize_tdesc_tic6x_* functions.