Partially revert "swr: add prototypes for resample dsp functions"

Prototypes are not needed anymore now that the x86 functions don't
include resample_template.c

The DO_RESAMPLE_ONE macro is removed for that same reason as well.

Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
swr: remove obsolete resample prototypes

Signed-off-by: James Almer <jamrial@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>