gdb/regformats: remove unused regformats/reg-*.dat

gdb/regformats: remove unused regformats/reg-*.dat

I believe that the .dat files starting with `reg-` are the manually
written ones, the other being generated from xml files from the features
directory.

This patch removes the manually-written files that are no longer needed.
They are unused since the recent series that removed a bunch of
gdbserver ports.

gdb/ChangeLog:

	* regformats/reg-arm.dat: Remove.
	* regformats/reg-bfin.dat: Remove.
	* regformats/reg-cris.dat: Remove.
	* regformats/reg-crisv32.dat: Remove.
	* regformats/reg-m32r.dat: Remove.
	* regformats/reg-tilegx.dat: Remove.
	* regformats/reg-tilegx32.dat: Remove.

Change-Id: I55ab6e45e3d0d316cda93f863c51fc9b867adfaa