soc: qcom: bam_dmux: Correct copyright dates

"msm: sps: remove sps header file" incorrectly updated the copyright dates
for bam_dmux_private.h.  As the file has modifications in the years 2013
and 2014, both years should be listed in the copyright.

Update the copyright dates to correctly list all years where in the file
was modified.

Change-Id: Ic917a6c25cdee5b2ed0d2fd7cf1131021fc7377a
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>