dmaengine/amba-pl08x : reset phychan_hold on terminate all

When a client calls pl08x_control with DMA_TERMINATE_ALL, it is correct
to terminate and release the phy channel currently in use (if one is in use),
but the phychan_hold counter must also be reset (otherwise it could get
trapped in an unbalanced state).

Signed-off-by: Davide Ciminaghi <ciminaghi@gnudd.com>
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>