Staging: speakup: Add helper macro for spk_synth boilerplate

For simple modules that contain a single spk_synth without
any additional setup code then ends up being a block of
duplicated boilerplate. This patch adds a new macro,
module_spk_synth(), which replaces the
module_init()/module_exit() registrations with template
functions.

Signed-off-by: Vaishali Thakkar <vthakkar1994@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>