Remove sysdeps/sh/soft-fp directory.

As per <https://sourceware.org/ml/libc-alpha/2014-10/msg00369.html>,
there should not be separate sysdeps/<arch>/soft-fp directories when
those are used by all configurations that use sysdeps/<arch>, and,
more generally, should not be sysdeps/foo/Implies files pointing to a
subdirectory foo/bar.  This patch eliminates the sysdeps/sh/soft-fp
directory accordingly, merging its contents into sysdeps/sh.

Tested with build-many-glibcs.py that installed stripped shared
libraries for sh configurations are unchanged by this patch.

	* sysdeps/sh/Implies: Remove sh/soft-fp.
	* sysdeps/sh/soft-fp/sfp-machine.h: Move to ....
	* sysdeps/sh/sfp-machine.h: ... here.