package/freerdp: fix pulseaudio support

The name of the option to enable/disable support for pulseaudio has been
in flux in FreeRDP, soemtimes being WITH_PULSE, sometimes being the
erroneous WITH_PULSEAUDIO. Eventually, FreeRDP came to their feet, and
fixed it to WITH_PULSE everywhere.

Signed-off-by: Alexey Lukyanchuk <skif@skif-web.ru>
[yann.morin.1998@free.fr:
  - remove useless (obsolete) WITH_PULSEAUDIO
  - fix the else clause too
  - enhance commit log
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>