spi : spi_qsd : Initialise complete signal only once in probe

Initialise complete signal only once in driver probe and do
reinitialise in the spi transfer function for the later uses
of the complete signal.

Change-Id: Ia12ada9ce7cf2552c10f5c2a7d90c1f4c7204647
Signed-off-by: Prudhvi Yarlagadda <pyarlaga@codeaurora.org>