staging: vt6655: Remove unused declaration of RFbAL7230SelectChannelPostProcess()

staging: vt6655: Remove unused declaration of RFbAL7230SelectChannelPostProcess()

Remove unused function RFbAL7230SelectChannelPostProcess declared in
rf.h but has no associated implementation.

Commit dd2837bdea0e removed the RFbAL7230SelectChannelPostProcess() but
accidentally forgot to delete the declaration in the header file.

Fixes: dd2837bdea0e ("staging: vt6655: Remove unused byRFType in rf.c")
Signed-off-by: Dorine Tipo <dorine.a.tipo@gmail.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/20240316204207.1779-1-dorine.a.tipo@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>