platform: msm: Export usb_bam symbols for module compilation

Some symbols utilized by f_qdss are not exported, which leads to symbol
undefined errors when compiling usb_bam as a module.  Export the symbols
remaining symbols used by f_qdss.

Change-Id: I3f01cee19bbbc990487df4437e15c3c5aa2a98e5
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>