rbcodec dsp: Move dsp_sample_io_configure() to its own file

Makes dsp_sample_input.c a bit less messy, and dependencies
are more explicit. There's possibly a minor loss of inlining
but it isn't a big deal.

Change-Id: I30f923a0ca758f2b113d32852d1f65586dff0cd1

lib/rbcodec/SOURCES

@@ -11,6 +11,7 @@ dsp/afr.c
 dsp/surround.c
 dsp/dsp_filter.c
 dsp/dsp_misc.c
+dsp/dsp_sample_io.c
 dsp/dsp_sample_input.c
 dsp/dsp_sample_output.c
 dsp/eq.c