test: improve cache flushing
test: improve cache flushing

Invalidate before sending, just in case the pages drop out of the cache.

Signed-off-by: Felipe Contreras <de77a8b9cd239b204c19c52ed62e48ab47243362@gmail.com>

felipec/dsp-tools,maemo-foss/maemo-multimedia-dsp-tools,maemo-foss/maemo-multimedia-dsp-tools