drm: msm: dsi-staging: Fix error handling in case of EPROBE_DEFER

When mdss pll probe fails with status EPROBE_DEFER, mdss pll probe is
called again and frees dfps data memory again causing the double free
and the crash. To avoid this, parse dfps data memory when mdss pll
probe is successful.

When devm_clk_get returns error in dsi_ctrl_clocks_init, initialise the
clk to NULL to avoid NULL pointer dereference in dsi_ctrl_clocks_deinit.

Change-Id: I4179b711f70c033729a3c8a57f93737e414bd02c
Signed-off-by: Ritesh Kumar <riteshk@codeaurora.org>