msm: sps: adapt to clock API change

With the change in clock driver, clk_get() can return -EPROBE_DEFER even
when the clock is actually present in HW. Thus, we need to return
-EPROBE_DEFER in SPS driver probe function if clk_get() fails.

Change-Id: Ia1b9f18425ca5432f4a56419adf142f2674ce64a
Signed-off-by: Yan He <yanhe@codeaurora.org>