msm_fb: hdmi: Return proper clock get error code

This change returns the proper error code while in probe and trying
to get the required clock and fails. This is required for probe deferral
support.

Change-Id: Ief91b1f634c06d3679157313506b56e5948aa79c
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>