ALSA: echoaudio: Use standard C definitions of true and false

The echoaudio locally defines TRUE and FALSE.  Not only is this
redundant given that C now has a boolean type it results in lots of
warnings as other headers also define these macros, causing duplicate
definitions.  Fix this by removing the local defines and converting all
local users to use the standard C true and false instead, simply
removing the macros is less safe due to implicit inclusion of the other
definitons.

[fixed overlooked replacement of FALSE by tiwai]

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>